Sahih Muslim 323
صحيح مسلم#323SahihHakim b. Hizam reported to 'Urwa b. Zubair that he said to the Messenger of Allah:Do you think that there is any thing for me (of he reward with the Lord) for the deed of religious purification that I did in the state of ignorance? Upon this he (the Messenger of Allah) said to him: You accepted Islam with all the previous virtues that you practised
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 1:230