Ascension. One night in 620 C.E ., after the deaths of Abu Talib and Khadija when the Holy Prophet felt sad and disconsolate, and things for Islam appeared to be dark, the Holy Prophet was uplifted to the Heavens, and there he was assured of the destiny of Islam. After this experience of ascension the Holy Prophet declared that the previous night he had been carried from Makkah to Masjid al Aqsa at Jerusalem, and from there he had ascended to the heavens.
Reaction of the people. When the non-believing Quraish heard of this visitation to the heavens, they regarded it as an absurdity, and ridiculed the Holy Prophet for his declaration. They contended that a caravan took a month to reach Jerusalem, and another month to come back, and thus it was impossible for any one to go to Jerusalem and return in one night. They further held that it was fantastic that a man should ascend the heavens.
Reaction of Abu Bakr. There were some Muslims as well who wavered in their belief in the truth about the ascension of the Holy Prophet to the heavens. Some persons went to Abu Bakr, and told him of the news of the journey of the Holy Prophet to Jerusalem and ascension to the heavens. When some persons expressed doubts about the veracity of the ascension, Abu Bakr silenced them with the remarks: "There are many things beyond one's comprehension, and if Muhammad (peace be on him) says that he went to Jerusalem and ascended the heavens, it must be true for he never tells a lie, and being a prophet he commands resources that are not available to others."
Witness to truth. On hearing the news, Abu Bakr hastened to the mosque where the Holy Prophet was describing his nocturnal journey to the people who had assembled there. After hearing the account, Abu Bakr stood up and said: "All this is true. Your description is faithful and correct. I believe in every word of what you have said, for you say nothing but the truth. I testify that you are the Messenger of God, and God has placed invisible forces at your disposal. As such there is nothing improbable in your ascension to the heavens."
Siddiq-the Veracious. The Holy Prophet felt happy at what Abu Bakr had said. Addressing Abu Bakr, the Holy Prophet said: "Verily, Abu Bakr you are the Siddiq. You have a penetrating vision and you can discern the truth which an ordinary person finds difficult to understand. Surely many things can be done under the command of Allah which ordinary human intellect may not be able to grasp." That is how Abu Bakr got the honorific title of 'Siddiq'- the Veracious (Witness to Truth), which henceforward became a part and parcel of his name.