Musnad Abu Ya'la al-Mawsili 153:107

Husayn ibn al-Aswad al-Kufi narrated to us, Muhammad ibn Bishr al-'Abdi narrated to us, Sufyan ibn Sa'id narrated to us, from Musa ibn 'Uqbah, from Salim, from Ibn 'Umar, who said: The oath of the Prophet, may Allah bless him and grant him peace, by which he would swear was: "No, and by the Turner of hearts."