Sahih al-Bukhari 3660
Sahih al-Bukhari · Book 62: Companions of the Prophet · "If I were to take Khalil ..."
Narrated `Ammar:
حَدَّثَنِي أَحْمَدُ بْنُ أَبِي الطَّيِّبِ ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ مُجَالِدٍ ، حَدَّثَنَا بَيَانُ بْنُ بِشْرٍ ، عَنْ وَبَرَةَ بْنِ عَبْدِ الرَّحْمَنِ ، عَنْ هَمَّامٍ ، قَالَ سَمِعْتُ عَمَّارًا ، يَقُولُ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم وَمَا مَعَهُ إِلاَّ خَمْسَةُ أَعْبُدٍ وَامْرَأَتَانِ وَأَبُو بَكْرٍ.
I saw Allah's Messenger (ﷺ) and there was none with him but five slaves, two women and Abu Bakr (i.e. those were the only converts to Islam then).