(76) باب مَا يُؤْمَرُ بِهِ الْمَأْمُومُ مِنَ اتِّبَاعِ الإِمَامِ
Al-Bara who is not a liar said; when they (the companions) raised their heads from bowing along with the Messenger of Allah (ﷺ), they would stand up, and when they saw him that he went down in prostration, they would prostrate (following the prophet).
Reference: Sunan Abi Dawud 620
In-book reference: Book 2, Hadith 230
English translation: Book 2, Hadith 620