Sahih Muslim
The Book of Destiny (Kitab-ul-Qadr)
Book Number: 033 / Hadith Number: 6418
Abdullah b. Amr b. al-'As reported that he heard Allah's Messenger (may peace be upon him) as saying: Verily, the hearts of all the sons of Adam are between the two fingers out of the fingers of the Compassionate Lord as one heart. He turns that to any (direction) He likes. Then Allahs Messenger (may peace be upon him) said: 0 Allah, the Turner of the hearts, turn our hearts to Thine obedience.