Musnad Abu Ya'la al-Mawsili 159:65

And with his chain of narration, that the Prophet, may Allah bless him and grant him peace, said: "O Allah, I take with You a covenant that You will not break. For I am only a human being; whichever of the believers I have struck, or insulted, or harmed, or cursed, then make it for him a mercy, a purification, and a means of nearness by which You bring him near to You on the Day of Resurrection."