Musnad Ahmad 28:134

Yahya ibn Ghaylan narrated to us, Rashdin narrated to us, Abu Hani al-Khawlani narrated to me, from Abu Abd al-Rahman al-Hubuli, from Abdullah ibn Amr ibn al-As, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The heart of the son of Adam is between two fingers of the fingers of the Compeller (al-Jabbar), Mighty and Majestic is He. If He wills to turn it, He turns it." He (the Prophet) used to say frequently: "O Turner of hearts."