Musnad Ahmad 100:6

'Affan narrated to us, Wuhayb narrated to us, 'Abdullah ibn 'Uthman ibn Khuthaym narrated to us, from Mujahid, from al-Sa'ib ibn Abi al-Sa'ib, that he used to be a partner of the Messenger of Allah, peace and blessings of Allah be upon him, in trade before Islam. When the day of the Conquest came, he came to him, and the Prophet, peace and blessings of Allah be upon him, said: "Welcome to my brother and my partner, who used to neither deceive nor dispute." "O Sa'ib, you used to perform deeds in the Pre-Islamic period (Jahiliyyah) that were not accepted from you, and today they are accepted from you." And he was a man of good conduct and kinship.