The very first person to accept Islam was the beloved wife of Rasulullah (sallallahu ‘alaihi wasallam), Hazrat Khadijatul Kubraa (radhiyallahu ‘anha). She was also the very first person to perform salaah with Rasulullah (sallallahu ‘alaihi wasallam) in jamaat on a Monday evening. Hence, she is regarded as the first of the Ahl-e-Qiblah (first of the muslims to perform salaah).

Thereafter, Hazrat Waraqah bin Nawfal (radhiyallahu ‘anhu) was honored with embracing Islam. After Hazrat Waraqah bin Nawfal (radhiyallahu ‘anhu), Hazrat ‘Ali (radhiyallahu ‘anhu), who had been in the care of Rasulullah (sallallahu ‘alaihi wasallam) for some time, accepted Islam at the age of ten.

On Tuesday, one day after Rasulullah (sallallahu ‘alaihi wasallam) was blessed with prophethood, he also performed salaah with Rasulullah (sallallahu ‘alaihi wasallam) in jamaat.

(Extracted from Seeratul Mustafa 1/154-155)