Musnad Ahmad 937:80

Hashim ibn al-Qasim narrated to us, 'Abd al-Hamid narrated to us, Shahr narrated to us, Ibn Ghanm narrated to me, that Abu Dharr narrated to him, from the Messenger of Allah (may Allah bless him and grant him peace), who said: "Indeed, Allah the Almighty and Majestic says: 'O My servant, as long as you worship Me and hope in Me, I will forgive you for what is in you. O My servant, if you were to meet Me with the earth full of sins, provided you do not associate anything with Me, I would meet you with its equivalent in forgiveness.'"