Sahih al-Bukhari 6617
Sahih al-Bukhari · Book 82: Divine Will (Al-Qadar) · "... (Allah) comes in between a person and his heart"
Narrated `Abdullah:
حَدَّثَنَا مُحَمَّدُ بْنُ مُقَاتِلٍ أَبُو الْحَسَنِ ، أَخْبَرَنَا عَبْدُ اللَّهِ ، أَخْبَرَنَا مُوسَى بْنُ عُقْبَةَ ، عَنْ سَالِمٍ ، عَنْ عَبْدِ اللَّهِ ، قَالَ كَثِيرًا مِمَّا كَانَ النَّبِيُّ صلى الله عليه وسلم يَحْلِفُ ( لاَ وَمُقَلِّبِ الْقُلُوبِ).
When taking an oath, the Prophet (ﷺ) very often used to say, "No, by Him Who turns the hearts."