Hadith 2387
Sayyiduna Ibn Umar (may Allah be pleased with them both) said: The oath of the Messenger of Allah (peace and blessings be upon him) used to be like this: «لَا وَمُقَلِّبِ الْقُلُوْبِ» No, by the One who turns the hearts «وَاللّٰهُ اَعْلَمُ بِالصَّوَابِ» .