Musannaf Ibn Abi Shayba 28:905

Safwan ibn Isa narrated to us, from al-Harith ibn Abi Dhubab, from Munir ibn Abdullah, from his father, from Sa’d ibn Abi Dhubab, who said: I came to the Messenger of Allah (may Allah bless him and grant him peace) and I accepted Islam. I said: "O Messenger of Allah, grant my people [the right to keep] what they have accepted Islam upon." The Messenger of Allah (may Allah bless him and grant him peace) did so.