Musnad Ahmad 100:1

Aswad ibn Amir narrated to us, Israel narrated to us, from Ibrahim—meaning Ibn Muhajir—from Mujahid, from al-Sa’ib ibn Abdullah, who said: I was brought to the Prophet, peace and blessings of Allah be upon him, on the day of the conquest of Mecca. Uthman ibn Affan and Zuhayr brought me, and they began to praise me. The Messenger of Allah, peace and blessings of Allah be upon him, said to them: "Do not tell me about him; he was my companion in the pre-Islamic era (Jahiliyyah)." He said: He said: "Yes, O Messenger of Allah, and what an excellent companion you were." He said: He then said: "O Sa’ib, look at the character traits you used to practice in the pre-Islamic era and apply them in Islam: honor the guest, be generous to the orphan, and be good to your neighbor."