حَدَّثَنَا مُحَمَّدُ بْنُ يُوسُفَ، عَنْ سُفْيَانَ، عَنْ مُوسَى بْنِ عُقْبَةَ، عَنْ سَالِمٍ، عَنِ ابْنِ عُمَرَ، قَالَ كَانَتْ يَمِينُ النَّبِيِّ صلى الله عليه وسلم ‏"‏ لاَ وَمُقَلِّبِ الْقُلُوبِ ‏"‏‏.‏
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."