On the authority of Anas, who said: I heard the messenger of Allah say:

Allah the Almighty has said: "O son of Adam, so long as you call upon Me and ask of Me, I shall forgive you for what you have done, and I shall not mind. O son of Adam, were your sins to reach the clouds of the sky and were you then to ask forgiveness of Me, I would forgive you. O son of Adam, were you to come to Me with sins nearly as great as the earth and were you then to face Me, ascribing no partner to Me, I would bring you forgiveness nearly as great as its."

Related by Al-Tirmithi, who said that it was a good and sound Hadith.