|Allâh has promised to those amongst you who believe and do righteous actions that He will certainly grant them khilâfah (succession) on the earth, as He granted it to those before them; and that He will grant them authority to practice their religion, the one that He has chosen for them; and He will change their state from one of fear in which they lived to one of peace and security. They will worship Me alone, not associating any partner with Me. But whosoever disbelieves after this, then they are the rebellious ones. 
Al-Hâfidh Ibn Kathîr (d.774H) – rahimahullâh – said:
This is a promise from Allâh – the Most High – to His Messenger, may the prayers of Allâh and the peace be upon him, that He will make his Ummah the khulafâ (successors) upon the earth. Meaning that they will be the leaders and rulers over mankind, by which nations will be corrected and to whom mankind will submit. And that He will replace their state of fear in which they lived, to one of security and dominion. Allâh – the Blessed, the Most High – has fulfilled His promise, and to Him belongs all praise and thanks. For the Prophet sallallâhu alayhi wa sallam did not die until Allâh made him conquer Makkah, Khaybar, al-Bahrain, the remaining lands of the Arabian peninsula and the whole of Yemen. He took jizyah corn the magians of Hajar and from the people of the surrounding areas of Syria. The Prophet sallallâhu alayhi wa sallam received gifts from Heraclius – the king of Rome; the ruler of Egypt and Alexandria – the Mawqawqis; the kings of Omân; and Negus, the king of Ethiopia, who became king after Ashamah died – may Allâh have mercy upon him and grant him nobility.
After the Messenger of Allâh sallallâhu alayhi wa sallam died, Allâh having chosen for him the reward which is with Him, Abû Bakr as-Siddîq was then established as his Khalîfah (successor), taking charge unwaveringly. Abû Bakr took the Arabian peninsula and put it in order. He sent forth the armies of Islâm to the lands of Persia, under the command of Khâlid ibn al-Walîd, radiallâhu anhu. They conquered parts of these lands, slaying a number of its inhabitants. A second army was sent to the lands of Syria, under the leadership of Abû Ubaydah – radiallâhu anhu – and those who followed him. A third army was sent to Egypt under the leadership of Amr ibn al-Âs radiallâhu anhu. It was during his time that the armies sent to Syria conquered the cities of Busra, Damascus and its environs from the land of Hawrân and its surroundings. Allâh – the Mighty and Majestic – took Abû Bakrs soul – choosing for him the reward which is with Him. Allâh blessed the people of Islâm by inspiring as-Siddîq to choose Umar al-Fârûq as a successor.
Umar then stood up, taking charge completely. The heavens will not witness – after the Prophets – anyone like Umar, whether in the strength of his reign or the fulfillment of justice. It was during his time that the conquest of Syria was completed; as was that of Egypt to its farthest reaches, as well as the province of Persia. He destroyed Kisrâ (Chosroes) and humiliated him to the utmost, forcing him to retreat back to the furthest reaches of his kingdom.
Similarly, Umar destroyed Qaysar (Caesar), wresting from his hands the lands of Syria and bottling him up in Constantinople. He spent the wealth (conquered from them) in the path of Allâh – as the Messenger of Allâh had informed and promised – may the most complete salâm and most purest salâh be upon the Messenger from his Lord.
Then there was the rule of Uthmân, under whom the possessions of Islâm extended to the furthest eastern and western reaches of the earth. The lands of the west were conquered to the farthest reaches of what lies there – Andalus, Cyprus, the lands of Qairawân and the lands of Ceuta – which is next to the all-encompassing ocean; and to the farthest lands of China. Kisrâ was killed and his kingdom totally vanquished. The cities of al-Irâq, Khurasân and Ahwâz were conquered and the Muslims slew a large number of Turks. Allâh having humiliated the Turks and their great king the Kha-Khan. The wealth of the east and the west was collected and brought to the Amîrul-Muminîn (leader of the Believers) Uthmân ibn Affân, radiallâhu anhu. All this came about as a result of the blessings of his recitation, study and gathering the Ummah upon the preservation of the Qurân.
It is confirmed in the Sahîh  that the Messenger of Allâh sallallâhu alayhi wa sallam said:
| Indeed Allâh gathered up the earth for me, so that I saw its east and west. Indeed, the dominion of my Ummah will reach what gathered up for me, from it.
We fluctuate in what Allâh has promised us with and in what His Messenger has promised. Allâh and His Messenger have spoken the truth. We ask Allâh to grant us îmân (faith) in Him and His Messenger, and that we establish gratitude for what Allâh has given us, in the manner that He is pleased with.
Imâm Muslim ibn al-Hajjâj said in his Sahîh, that Ibn Abî Umar related to us, that Sufyân related to us from Abdul-Maiik ibn Umayr, from Jâbir ibn Samarah who said: I heard the Messenger of Allâh, sallallâhu alayhi wa sallam say:
| The affair of the people will continue to remain upright while twelve men are in charge of them.
The Prophet sallallâhu alayhi wa sallam then said something which I could not make out. So I asked my father: What did the Messenger of Allâh, sallallâhu alayhi wa sallam, say? He replied: They are all from Quraish. This narration is also reported by al-Bukhârî. 
In this narration there exists a clear evidence that all twelve of these men must be leaders from Quraish. They are not the twelve imâms claimed by the Shîah, because many of them had no leadership over the Muslims. As for these twelve, they will be from Quraish and they will be just rulers. The glad tidings of their appearance has also occurred in the previous scriptures. Furthermore it is not necessary that they succeed one another. Rather, their appearance in the Ummah could be successive or separate. Four of them were in order, namely, Abû Bakr, Umar, Uthmân and Alî, radiallâhu anhum. After these four there was a gap. Others amongst the twelve appeared as and when Allâh willed. It is possible that some of them will appear during a time only which Allâh – the Most High – knows. Among them will be the Mahdî whose name will be that of the Messenger, sallallâhu alayhi wa sallam, and his kunyâ that of his kunyâ. He will fill the earth with justice as it is filled with tyranny and injustice.
Imâm Ahmad, Abû Dâwûd, at-Tirmidhî and an-Nasâî have all reported from the hadîth of Saîd ibn Juhmân, from Safînah – the mawlâ of the Messenger of Allâh sallallâhu alayhi wa sallam, that the Messenger of Allâh sallâllâhu alayhi wa sallam said:
| The Succesorship (al-Khilâfah) after me will last for thirty years. Then kingship will appear. 
Ar-Rabî ibn Anas has said that Abûl-Âliyah has remarked concerning this verse:
|The Prophet, sallallâhu alayhi wa sallam, and his Companions were in Makkah for ten years afraid, secretly calling to Allâh and His worship alone, He has no partner. They remained in such a state until they were ordered to migrate to Madînah. They were ordered by Allâh to fight. While they were (in Madînah) they were in constant fear (of attack). They would go to sleep armed and awake armed. They remained patient upon that state as long as Allâh willed. Until one day, one among the Companions said: O Messenger of Allah! Will we remain in a state of fear until the end of time? Will there not come a day when we will be in a state of security, so we may lay down our weapons? The Messenger of Allâh, sallallâhu alayhi wa sallam, then said: Be patient for a while. For there will come a time when any man from you would sit in a large crowd unarmed. Allâh sent down this verse and made His Prophet victorious over the Arabian Peninsula. The Prophets Companions were now safe and could lay down their weapons. Allâh – the Most High – then took the soul of His Prophet, sallallâhu alayhi wa sallam, and the Muslims remained in such a state during the leadership of Abû Bakr, Umar and Uthmân. Until the Muslims fell into what they fell into from discord. So fear entered their hearts and they took armies and guards for protection. For they had changed, so Allâh changed their state.
One of the Salaf has remarked that the khilâfah of both Abû Bakr and Umar is true. He then recited this verse. Al-Bara ibn Azîb has said:
|This verse was revealed while we were in a state of extreme fear.
This noble verse is similar in meaning to His statement – the Most High:
|And remember when you were few and were reckoned weak in the land and were afraid that men might kidnap you, but He (i.e. Allâh) provided a safe place for you, and strengthened you with His help and provided you good things so that you might be grateful. 
His statement – the Most High: as he granted that to those before them. This verse is similar to what Allâh has said about Mûsa, alayhis salâm, that he said to his people:
|It may be that your Lord will destroy your enemy and make you succeed (the present rulers) on earth, so that He may see how you act. [7 ]
And Allâh – the Most High – has said:
|And We wished to confer a favour upon those who were oppressed in the land; and to make them leaders and to make them heirs; and to establish them on earth… 
And Allâhs statement: And that He will change their state after the fear in which they lived to one of security and peace. This is similar to what the Messenger of Allâh, sallallâhu alayhi wa sallam, said to Adî ibn Hâtim when Adî came as a delegation to the Messenger
| . The Messenger said: Do you know Hira? Adî replied: I have not seen it but I have heard of it. The Messenger then said: By Him in Whose Hand is my soul! Allâh will complete this matter (i.e. Islâm) until a woman will be able to travel from Hira until she goes around the House (i.e. the Kabah) not needing the protection of anyone. And you will certainly conquer the treasures of Kisra ibn Hurmuz. I (i.e. Adî) replied: Kisra ibn Hurmuz! The Prophet replied: Yes! Kisra ibn Hurmuz. Money will be spent until no-one will accept it. Adî ibn Hâtim said: Now here is the woman leaving from Hira until she goes around the House. And I was among those who conquered the treasures of Kisra. And by Him in Whose Hand is my soul! The third matter will come to pass because the Messenger of Allâh, sallallâhu alayhi wa sallam, has said so.
Ahmad reports upon Ubayy ibn Kab who said that the Messenger of Allâh, sallallâhu alayhi wa sallam, has said:
| Give good news to this Ummah of ease of life, exalted stature, establishment of their religion, victory and leadership on earth. Whoever does acts of the Hereafter for this world, he will have no portion of the Hereafter. 
And Allâhs statement: They worship Me alone and do not associate anything with Me. Ahmad reports upon Muâdh who said;
| I was sitting behind the Prophet, sallallâhu alayhi wa sallam, on a donkey. There was nothing between the Prophet, sallallâhu alayhi wa sallam, and I except the end of his saddle. The Prophet said to me: O Muâdh ibn Jabal! I said: Here I am O Messenger of Allâh in your service. The Prophet continued to ride on for some time and then he said to me: O Muâdh ibn Jabal! I said; Here I am O Messenger fo Allâh in your service. The Prophet said: Do you know what is the right of Allâh upon His slave? I said: Allâh and His Messenger know best. He said: The right of Allâh upon the slaves is that they worship Him and do not associate anything with Him. The Prophet continued to ride on for some time and then he said to me: O Muâdh ibn Jabal! I said: Here I am O Messenger of Allâh, at your service. The Prophet said: Do you know what is the right of the slaves upon Allâh if they (worship Him alone)? I said: Allâh and His Messenger know best. He said: The right of the slaves upon Allâh is that He does not punish whosoever does not associate anything with Him. This narration is also reported in the two Sahîhs. 
And Allâhs statement: But whoever disbelieved after this, they are the rebellious ones. Meaning: Whoever steps outside of my obedience after that promise, he has stepped outside of the Command of His Lord, and sufficient is that as a great sin. Since the Prophets Companions, radiâllâhu anhum were the most upright and obedient of people after the Prophet, sallallâhu alayhi wa sallam, in fulfilling the Commands of Allâh – the Mighty and Majestic – their victory was accordingly. The Companions of the Prophet made the Word of Allâh supreme, so Allâh Himself aided hem in such a manner that He subdued for them the rest of mankind, as well as their lands.
When the people after the Prophets Companions fell short in adhering to some of Allâhs Commands, their victory accordingly fell short. It is, however, affirmed in both Sahîhs (i.e. al-Bukhârî and Muslim) in many ways from the Messenger of Allâh sallallâhu alayhi wa sallam that he said:
| There will not cease to be a group from my Ummah victorious, upon the Truth, not being harmed by those who abandoned them or go against them, until Allâhs affair comes, and they are like that. And in a narration: Until the last of them fights Masîhud-Dajâl. [12 ]And in a narration: They will be victorious until the Day of Judgement, then Îsâ ibn Maryam will descend. 
All these narrations are authentic and there is no contradiction between any of them.
Shaykh Abdur-Rahmân as-Sadî (d.1376H) said: 
| This is one of His true promises whose meaning and accomplishment has been witnessed. He promised those who came with îmân (faith) and amalus-sâlih (righteous and correct actions) from this Ummah, that He will cause them to be the successors upon this earth, so that they are the ones in authority and in charge of the affairs. Further, that He would establish their Dîn – that which He was pleased with for them, which is the Dîn of Islâm, which gained ascendancy over all other religions. He was pleased with it for this Ummah, due to its excellence, nobility and His favours upon it, in that He enabled them to establish it, and to establish its laws and prescriptions – relating both to manifest and non-manifest matters – upon themselves and upon others, so that the people of other religions and the rest of the unbelievers are conquered and humbled.
And that He would change their condition of fear to one of security, since it was previously the case that one of them would not be able to manifest his Dîn, and they suffered harm and injury from the unbelievers. The united body of Muslims was very small in number, in comparison to to the rest of the people of the earth, who combined to attack them and hope for their downfall.
However, Allâh promised them these things when the âyah was sent down, at a time when they were not witnessing ascendancy and establishment upon the earth, nor the ability to fully establish the Dîn of Islâm and full security – such as would enable them to worship Allâh, not associating anything with Him – in a state of not having to fear anyone except Allâh.
So the first and foremost ones of this Ummah combined îmân and righteous and correct action to a degree surpassing everyone else, so He established them in the land and gave them authority over the people, and granted them the conquest of the east and the west. They attained full security and complete authority and establishment – and this one of the astounding Signs of Allâh.
This applies until the Hour is established – that whenever the Muslims combine îmân and righteous and correct action -then that which Allâh promises will certainly occur. Indeed, Allâh only grants that they be overcome by the unbelievers and the hypocrites, and that they suffer humiliation when the Muslims neglect îmân and righteous and correct action.
Article Taken from www.sunnahonline.com
1. Sûrah Nûr 24:55
2. Tafsîr Qurânul-Adhîm (3/311-313).
3. Related by Muslim (8/171) and also Abû Dâwûd (no.4252), from Thawbân radiallâhu anhu.
4. Related by al-Bukhârî (6/416), Muslim (6/3-4) and also Ahmad (5/101), the wording is from Ahmad.
5. Sahîh: Related by Abû Dâwûd (no.4646), at-Tirmidhî (2/35) and others. It was authenticated by at-Tabarî in his Itiqâd (p.8) and al-Hâfidh Ibn Hajar in Fathul-Bârî (13/182).
6. Sûrah Anfâl 8:26
7. Sûrah Arâf 7:129
8. Sûrah Qasas 28:5-6
9. Sahîh: Related by Ahmad (4/134) and al-Hâkim (4/311) and it was authenticated by al-Albânî in Ahkâmul-Janâiz (p.52).
10. Related by al-Bukhârî (6/58) and Muslim (1/232).
11. Related by Muslim (6/52-53) and at-Tirmidhî (2/36) from
Thawbân radiallâhu anhu.
12. Sahîh: Related by Ahmad (4/429), Abû Dâwûd (1/388-389) and al-Hâkim (4/450), from Imrân ibn Husayyin radiallâhu anhu. It was authenticated by al-Albânî in as-Sahîhah (no.1959).
13. Related by Imâm Muslim (l/95) and Ahmad (3/384) from Jâbir radiallâhu anhu.
14. Taysîrul-Karîmir-Rahmân (4/123).