Chapter: If a person stands by the left side of the Imam, and the Imam dress him to the right from behind, the Salat (prayer) is correct.
Narrated Ibn `Abbas:I prayed with the Prophet (ﷺ) one night and stood on his left side. Allah's Messenger (ﷺ) caught hold of my head from behind and drew me to his right and then offered the prayer and slept. Later the Mu'adh-dhin came and the Prophet (ﷺ) stood up for prayer without performing ablution.
Reference
Sahih al-Bukhari 726
In-book reference
Book 10, Hadith 120
USC-MSA web (English)
Vol. 1, Book 11, Hadith 693
Translation by Dr. M. Muhsin Khan · Language: EN
Sahih
Arabic Text
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا دَاوُدُ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ كُرَيْبٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ صَلَّيْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم ذَاتَ لَيْلَةٍ فَقُمْتُ عَنْ يَسَارِهِ، فَأَخَذَ رَسُولُ اللَّهِ صلى الله عليه وسلم بِرَأْسِي مِنْ وَرَائِي، فَجَعَلَنِي عَنْ يَمِينِهِ، فَصَلَّى وَرَقَدَ فَجَاءَهُ الْمُؤَذِّنُ، فَقَامَ وَصَلَّى وَلَمْ يَتَوَضَّأْ.