Sahih al-Bukhari 728
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · The right side of the mosque and the place to the right of the Imam
Narrated Ibn `Abbas:
حَدَّثَنَا مُوسَى ، حَدَّثَنَا ثَابِتُ بْنُ يَزِيدَ ، حَدَّثَنَا عَاصِمٌ ، عَنِ الشَّعْبِيِّ ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ قُمْتُ لَيْلَةً أُصَلِّي عَنْ يَسَارِ النَّبِيِّ صلى الله عليه وسلم فَأَخَذَ بِيَدِي أَوْ بِعَضُدِي حَتَّى أَقَامَنِي عَنْ يَمِينِهِ، وَقَالَ بِيَدِهِ مِنْ وَرَائِي.
One night I stood to the left of the Prophet (ﷺ) in the prayer but he caught hold of me by the hand or by the shoulder (arm) till he made me stand on his right and beckoned with his hand (for me) to go from behind (him). (Al-Kashmaihani [??] , Fath-ul-Bari).