Sahih al-Bukhari 699
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · If the Imam has not had the intention of leading the prayer and then some persons join him and he leads them
Narrated Ibn `Abbas:
حَدَّثَنَا مُسَدَّدٌ ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ ، عَنْ أَيُّوبَ ، عَنْ عَبْدِ اللَّهِ بْنِ سَعِيدِ بْنِ جُبَيْرٍ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ بِتُّ عِنْدَ خَالَتِي فَقَامَ النَّبِيُّ صلى الله عليه وسلم يُصَلِّي مِنَ اللَّيْلِ، فَقُمْتُ أُصَلِّي مَعَهُ فَقُمْتُ عَنْ يَسَارِهِ، فَأَخَذَ بِرَأْسِي فَأَقَامَنِي عَنْ يَمِينِهِ.
Once I passed the night in the house of my aunt Maimuna. The Prophet (ﷺ) stood for the night prayer and I joined him and stood on his left side but he drew me to his right by holding me by the head.