Sahih al-Bukhari, Hadith 747 ⓘ
Narrated Al-Bara: (And Al-Bara was not a liar) Whenever we offered prayer with the Prophet and he raised his head from the bowing, we used to remain standing till we saw him prostrating.
حَدَّثَنَا حَجَّاجٌ، حَدَّثَنَا شُعْبَةُ، قَالَ أَنْبَأَنَا أَبُو إِسْحَاقَ، قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ يَزِيدَ، يَخْطُبُ قَالَ حَدَّثَنَا الْبَرَاءُ، وَكَانَ، غَيْرَ كَذُوبٍ أَنَّهُمْ كَانُوا إِذَا صَلَّوْا مَعَ النَّبِيِّ صلى الله عليه وسلم فَرَفَعَ رَأْسَهُ مِنَ الرُّكُوعِ قَامُوا قِيَامًا حَتَّى يَرَوْنَهُ قَدْ سَجَدَ.
also referenced under: Book 10, Hadith 141 (In-Book) & Volume 1, Book 12, Hadith 714 (USC-MSA)