On the day after Hazrat ‘Uthmaan (radhiyallahu ‘anhu) accepted Islam, Hazrat Abu Bakr (radhiyallahu ‘anhu) brought the following luminaries to Rasulullah (sallallahu ‘alaihi wasallam):
Hazrat ‘Uthmaan bin Maz‘oon (radhiyallahu ‘anhu), Hazrat Abu ‘Ubaidah bin Jarraah (radhiyallahu ‘anhu), Hazrat Abu Salamah bin ‘Abdil Asad (radhiyallahu ‘anhu) and Hazrat Arqam bin Arqam (radhiyallahu ‘anhu).
All of them embraced Islam together in one sitting.
Yazeed bin Rumaan narrates:
Hazrat ‘Uthmaan bin Maz‘oon (radhiyallahu ‘anhu), Hazrat ‘Ubaidah bin Haarith (radhiyallahu ‘anhu), Hazrat Abu ‘Ubaidah bin Jarraah (radhiyallahu ‘anhu), Hazrat ‘Abdur Rahmaan bin ‘Auf (radhiyallahu ‘anhu) and Hazrat Abu Salamah bin ‘Abdil Asad (radhiyallahu ‘anhu) all came together and presented themselves before Rasulullah (sallallahu ‘alaihi wasallam). Rasulullah (sallallahu ‘alaihi wasallam) invited them to accept Islam and informed them regarding the injunctions of Islam, after which they all accepted Islam together. All these personalities embraced Islam before they had taken refuge in Daar-e-Arqam.
(Extracted from Seeratul Musatafa 1/168)