Al-Ghafoor - The Forgiver of Sins
On the authority of Anas (may Allah be well pleased with him) who said, “I heard the Messenger of God ﷺ say: Allah ﷻ said:
‘O son of Adam, so long as you call upon Me and ask 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 it’
The hadith above was related by at-Tirmidhī (also by Ahmad ibn Hanbal).
Its chain of authority is sound.