I heard Abdullah bin Yazid al-Khatmi addressing the people. He said, "Al-Bara narrated to us, and he is no liar, that whenever they raised their heads from bowing with the Messenger of Allah ﷺ, they would remain standing, and when they saw him prostrate, they would then prostrate."
حدثنا حفص بن عمر حدثنا شعبة
سمعت عبد الله بن يزيد الخطمي يخطب الناس قال حدثنا البراء وهو غير كذوب أنهم كانوا إذا رفعوا رءوسهم من الركوع مع رسول الله ﷺ قاموا قياما فإذا رأوه قد سجد سجدوا
Bukhari narrated it, Adhan, Chapter on Raising the Gaze to the Imam During Prayer, no. 747, from the hadith of Shubah. Muslim also narrated it, Prayer, Chapter on Following the Imam and Acting After Him, no. 474, from the hadith of Abu Ishaq Sabi through this chain.