question #2 Sahih Muslim 474c, Book 4, Hadith 226 : How did the Companions ensure they were correctly performing the prayer with the Prophet?

They (the Companions) said prayer with the Messenger of Allah (ﷺ), and they bowed when he (the Holy Prophet) bowed. and when he raised his head after bowing, he pronounced:” Allah listened to him who praised Him,” and we kept standing till we saw him placing his face on the ground and then we followed him.