Rasulullah (sallallahu ‘alaihi wasallam) presented the truth and Hazrat Abu Bakr (radhiyallahu ‘anhu) submitted to it. A single tasdeeq (belief) transformed him into a siddeeq (passionate believer).

In one Hadith, Rasululullah (sallallahu ‘alaihi wasallam) said, “Every person to whom I presented Islam showed some degree of hesitation, except for Hazrat Abu Bakr (radhiyallahu ‘anhu). He embraced Islam without any hesitation at all.”

When Imaam Abu Hanifah (rahimahullah) was asked, “Who was the first person to embrace Islam?” he replied, “Among the free men, it was Hazrat Abu Bakr (radhiyallahu ‘anhu). Among the women, it was Hazrat Khadijah (radhiyallahu ‘anha). The first slave to embrace Islam was Hazrat Zaid bin Haarithah (radhiyallahu ‘anhu), while Hazrat ‘Ali (radhiyallahu ‘anhu) was the first child to enter the fold of Islam.”

(Extracted from Seeratul Mustafa 1/156)