Also called As-siddiq ("The Upright" in Arabic), Abu Bakr was approximately two years younger than the Prophet. Before embracing Islam, he was known as Abdul Ka'ba (the servant of Ka'ba), then the Prophet changed his name to Abdullah (the servant of God). 

Among the youth, frolics, dissipations and frivolities were very common behaviors, but Abu Bakr was completely different. He had a very disciplined life. Once he was asked if he had drunk wine in his days of ignorance. He said he had never touched the wine because he had wanted to keep his reputation and respectability. This shows that he enjoyed a good reputation and respectability even before Islam (Ibn al-Athir, 1280).

He did not receive a formal education as many other Arab men, but he was a keen observer; he was continually observing what was going on around him. He had a very good memory. He could recite verses if he heard them only once. He attended poetical events (Ibn al-Athir, 1280).

Abu Bakr traveled to different countries including Abyssinia, Yemen, and Syria. These business trips brought him wealth, experience and broadened his outlook on life. He became one of the richest businessmen of Mecca. Accordingly, his social importance increased among people. He was hardworking, generous, friendly, truthful, committed. He had a lot of influence among his friends and acquaintances. As a trader, he was always fair, he never deceived people. He would visit the sick; he gave alms to the poor (at-Tabar, 1987). One day the Prophet asked his people, "Is there anyone here who visited a sick one today?" Abu Bakr said, "I did." "Is there anyone who fasted today?" Abu Bakr said, "I did." "Is there anyone who participated in a funeral?" Abu Bakr said, "I did." "Is there anyone who assisted someone who was poor?" Abu Bakr said, "I did." Then the Prophet said, "Whoever does these four deeds in one day is counted among the people of heaven."

While Abu Bakr was still young, he volunteered for an office which decided the blood money for the killed or injured. It was like a judge or magistrate's office. He always satisfied both sides with his fair decisions. (at-Tabar, 1987).

When God's message was revealed to Muhammad, the first man to believe in him was Abu Bakr. On the day that he stated his belief, he gave his decision quickly and without hesitation showing he had complete trust in Muhammad. The Prophet admired his acceptance of Islam with the words, "Except Abu Bakr, everyone I have invited to Islam has experienced some period of hesitation. But Abu Bakr accepted my invitation without any hesitation" (Bukhari, 870). In fact, Abu Bakr had always doubted the validity of idolatry and had no enthusiasm for worshiping idols. 
When Islam began to spread in Mecca, Meccan polytheists inflicted torture and intimidation on the believers, forcing many of them to immigrate to Abyssinia. Yet, Abu Bakr did not leave. He preferred to stay with the Prophet to support him in his time of need. And he was going to be the company to the Prophet in the Hijrah, his historic journey to Medina, which would transform the course of history forever.

Later when the battles of Badr and Uhud took place between Muslims and the Arab pagans, Abu Bakr, along with a few other companions, was entrusted with the Prophet's safety. When Mecca was at last subdued in 630 AD, all the tribes of Arabia were convinced that Muhammad was a messenger sent to them by God. They stopped resisting and sent delegates to Medina proclaiming their allegiance to him. While he was busy receiving delegates, he entrusted Abu Bakr to preside over the pilgrims. This incident proved of vital importance later when a caliph was chosen after the death of the Prophet (Ibnal-Kathir, Isma'il, 1932).

His leadership
The Prophet made a pilgrimage two years after the conquest of Mecca. This would be called the "Farewell Pilgrimage," as the Prophet became ill on his return to Medina and died two weeks after the illness. During the last days of his illness, he could not lead the prayers in the Mosque. He gave instructions to his wife Aisha to tell her father Abu Bakr to lead the prayers. This was taken by the Muslims as another sign to choose Abu Bakr to be their caliph after the Prophet's departure (Ibn Hisham, 1992).

When the Prophet died in 632 AD, many people, among whom was 'Umar bin al-Khattab, were shocked and refused to believe that he died. But Abu Bakr, steadfast as usual, addressed the bewildered masses and convinced them that Muhammad was no more than a Prophet like other Prophets who had died before him, and that there was no reason why they should not acknowledge his death. After much debate, in which both sides-the Medinans and the Meccans-expressed their opinions elaborately and freely, Abu Bakr was unanimously accepted to be the first Caliph. Soon there was a public meeting in the Mosque, and people from near and far flocked there to swear their oath of allegiance to Abu Bakr (Ibn Hisham, 1992).

The Prophet Muhammad categorically rejected racism and tribalism. He also put an end to tribal wars. Sir William Muir makes the following comment:

The first peculiarity, then, which attracts our attention is the subdivision of the Arabs into innumerable bodies... each independent of the others: restless and often at war amongst themselves; and even when united by blood or by interest, ever ready on some significant cause to separate and give way to an implacable hostility. Thus at the era of Islam the retrospect of Arabian history exhibits, as in the kaleidoscope, an ever-varying state of combination and repulsion, such as had hitherto rendered abortive any attempt at a general union... The problem had yet to be solved, by what force these tribes could be subdued or drawn to one common center; and it was solved by Muhammad (Muir,1988).

Instead of tribalism and tribal attachment, the Prophet Muhammad instituted virtue and God-consciousness. He also instituted allegiance or public consent. People were free to elect their administrator. So after the Prophet's death, his followers came together and discussed among themselves who would be their new leader. Since the one who would lead the newly-established Muslim community would succeed the Prophet in his leadership in all things except Prophethood, he was named the Successor. The Caliph means the one who succeeds. So the leaders of the Muslim community after the Prophet's death were called Caliph.

1- The Wars of Apostasy
Abu Bakr had to struggle with apostates and false prophets. What elements caused the wars of apostasy? First, the death of the Prophet was a great shock to Muslims. For the first time in the lives of both the Meccans and the Medinans, they were united around a single religion. Their centuries-old customs and feudal or tribal values and understandings were abolished. Their absorption of the new system would not be easy. They accepted this system in the footsteps of the Prophet Muhammad. So his death was a great shock. Adoption of the new system was difficult especially for the newly-converted desert tribes. Some of them left the new religion and followed false prophets who appeared among them and called them back to their old customs.

Secondly, Islam instituted zakat (alms-giving or charity). It was collected from the rich and spent for the well-being of the poor and for the wayfarers left without money to complete their travel. It was also used for those who cannot pay their debts, and for those who strive in "God's cause". Some desert tribes refused to pay it after the Prophet's death. This signaled their revolt against the new administration in Medina.

Thirdly, the influence of the Romans from the north and the Persians and the Abyssinians from the east and the south encouraged the distant tribes to return back to their own beliefs and customs. (As?m, 1981).

Abu Bakr succeeded in putting down the rebellions and re-instituted unity in Arabia. His good reputation among people, his character, and his wise measures were influential in surpassing the rebellions and re-instituting the unity. He sent military units against the revolting tribes. In the end, those tribes gave up their disobedience.

2- Usame's punitive expedition
The changes brought about by the Muslims in Arabia drew the attention of the Roman (Byzantium) Empire. In order to prevent their growing strength, they sent armies. During the time of the Prophet , Roman and Muslim armies fought in Muta, on the border of Jordan. No side could overpower the other in this first encounter. One year before the Prophet's death, Romans organized another powerful army. On hearing this, the Prophet left Medina with his army and went as far as Tabuk, in the far north of Arabia. However, the Prophet's illness caused this army to stay in Madina without departing. After his death, due to the news of rebellions in some desert tribes, some Muslims wanted to cancel this expedition. But Abu Bakr, as the newly-chosen Caliph, firmly opposed the idea, saying: "I will never cancel anything initiated by the Prophet". The curious thing about this army was that it was made up of mostly the early Companions of the Prophet, but its leader was Usame ibn Zayd, who was only 18 years old. During the lifetime of the Prophet, his old Companions objected, but they were given a heated sermon in which both Usame and his father were praised as competent leaders (At-Tabar, 1987).

3- Compilation of the Qur'an
1200 Muslims were killed in the battle called Aqraba, among them were many who were committing the Qur'an to memory. Umar ibn al Khattab, whose brother Zayd was among the dead, thought deeply of what might happen if wars continued and more such people were killed. He reached the conclusion that if the Qur'an was to be preserved, it ought to be compiled into one volume. At that time, it was scattered among the companions of the Prophet, with each preserving certain portions of it. Methods of preservation differed. Some had it written on parchment; others on palm branches stripped of leaves; a third group was written on bones; and a fourth on stone tablets; a large number also memorized it by heart. If many of those who had memorized it were killed, then a part of the Holy Book might disappear. So Umar went to the caliph, who was then sitting in the Prophet's grand Mosque. He discussed his idea with him, but Abu Bakr rejected it because it was not something done by the Prophet. A lengthy debate followed, after which Abu Bakr was convinced that Umar was right (Ezzati, 1978).

Abu Bakr's compilation of the Qur'an is regarded by many as his most significant legacy. It was even more significant than the wars of apostasy and the conquest of Iraq and Syria. Ali ibn Abi Talib used to say: "May God have mercy upon Abu Bakr! He is worthy of being superbly rewarded because he was unique in compiling the Qur'an" (Ibn Hajar, 1988).