Musannaf Ibn Abi Shayba 23:100

Ghundar narrated to us, from Shu'bah, from al-Hakam ibn 'Uyaynah, who said: I heard Ibn Abi Layla narrating from the Prophet, may Allah bless him and grant him peace, that he used to supplicate with this supplication: "O Turner of the hearts, keep my heart firm upon Your religion."