Musnad Abu Ya'la al-Mawsili 153:106

Muhammad ibn 'Abbad al-Makki narrated to us, 'Abdullah ibn Raja' narrated to us, from 'Abbad ibn Ishaq, from al-Zuhri, from Salim, from his father, who said: The oath of the Prophet, may Allah bless him and grant him peace, was: "No, and [by] the Turner of hearts."