Sahih al-Bukhari 6644
Book 83: Oaths and Vows · Narrated by Anas bin Malik
Arabic
حَدَّثَنِي إِسْحَاقُ، أَخْبَرَنَا حَبَّانُ، حَدَّثَنَا هَمَّامٌ، حَدَّثَنَا قَتَادَةُ، حَدَّثَنَا أَنَسُ بْنُ مَالِكٍ ـ رضى الله عنه ـ أَنَّهُ سَمِعَ النَّبِيَّ صلى الله عليه وسلم يَقُولُ " أَتِمُّوا الرُّكُوعَ وَالسُّجُودَ، فَوَالَّذِي نَفْسِي بِيَدِهِ إِنِّي لأَرَاكُمْ مِنْ بَعْدِ ظَهْرِي إِذَا مَا رَكَعْتُمْ وَإِذَا مَا سَجَدْتُمْ ".
English translation
Narrated Anas bin Malik:I heard the Prophet (ﷺ) saying, "Perform the bowing and the prostration properly (with peace of mind), for, by Him in Whose Hand my soul is, I see you from behind my back when you bow and when you prostrate
Reference: Sahih al-Bukhari 6644, Book of Oaths and Vows. English translation by Dr. Muhammad Muhsin Khan.