#4 Behind the Imam
Book of Call to Prayers (Adhaan)
(52)
Chapter: When should those who are behind the Imam prostrate?
Hadith 690
Narrated Al-Bara:
(and he was not a liar) When Allah’s Messenger (صَلَّى ٱللَّٰهُ عَلَيْهِۦ وَسَلَّمَ) said, “Sami`a l-lahu liman hamidah” none of us bent his back (for prostration) till the Prophet (صَلَّى ٱللَّٰهُ عَلَيْهِۦ وَسَلَّمَ) prostrated and then we would prostrate after him.