From Sahih Muslim (Hadith 326):
Hisham b. Urwa narrated it on the authority of his father:Hakim b. Hizam freed one hundred slave and donated one hundred camels (for the sake of Allah) during the state of ignorance. Then he freed one hundred slaves and donated one hundred camel (for the sake of Allah) after) he had embraced Islam. He subsequently came to the Apostle (ﷺ). The rest of the hadith is the same as narrated above
Reference: Muslim 326