Sayyiduna Abu al-Darda' (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Your Lord says: If My servant comes to Me with sins filling the earth, while he does not associate anyone with Me as a partner, I will meet him with just as much forgiveness."
At-Tabarani recorded it, and its chain contains narrators whom I do not know.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التوبة / 17629