Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the most frequent oath of the Messenger of Allah (peace and blessings be upon him) was: “By «لا و مصرف القلوب»! And by the One Who turns the hearts.”

Sayyiduna Rifa‘ah bin ‘Arabah Juhani (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings of Allah be upon him) used to swear in this way: “By Him in Whose Hand is the life of Muhammad.”