‘Uthman (may Allah be pleased with him) reported Allah’s Messenger (peace be upon him) as saying, “When the time for a prescribed prayer comes, if any Muslim observes proper ablution, humility and bowing, it will be an expiation for his past sins, so long as he has not committed a major sin; and that means for all time.” Muslim transmitted it.
Mishkat al-Masabih 286, Book 3, Hadith 5
