Musannaf Ibn Abi Shayba 36:414

Affan narrated to us, he said: Wuhayb narrated to us, he said: Abdullah bin Uthman bin Khuthaym narrated to us, from Mujahid, from al-Sa’ib, that he used to be a partner of the Messenger of Allah, may Allah bless him and grant him peace, in trade before Islam. When the day of the Conquest came, he came to him, and he (the Prophet) said: "Welcome to my brother and my partner. He used to neither deceive nor dispute." "O Sa’ib, you used to perform deeds in the Jahiliyyah that were not accepted from you, and today they are accepted from you." And he was a man of noble lineage and kinship.