(88) باب الْخُشُوعِ فِي الصَّلاَةِ
Narrated Anas bin Malik:
The Prophet (ﷺ) said, "Perform the bowing and the prostrations properly. By Allah, I see you from behind me (or from behind my back) when you bow or prostrate."
Reference: Sahih al-Bukhari 742
In-book reference: Book 10, Hadith 136
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 12, Hadith 709