Musnad Ahmad 1290:3

Yunus ibn Muhammad narrated to us, Layth ibn Sa‘d narrated to us, Yazid ibn Abi Habib narrated to us, from Abu al-Nadr, from Kharijah ibn Zayd, from his mother, who said: When Uthman ibn Maz‘un passed away, Umm Kharijah bint Zayd said: "May you be blessed, Abu al-Sa’ib. Your days were the best of days." The Prophet of Allah (peace and blessings of Allah be upon him) heard her and said: "Who is this?" She said: "I am." He (peace and blessings of Allah be upon him) said: "And what makes you know [that]?" I said: "O Messenger of Allah, [it is] Uthman ibn Maz‘un." The Messenger of Allah (peace and blessings of Allah be upon him) said: "Yes, Uthman ibn Maz‘un. We have seen nothing but good. And I am the Messenger of Allah, and by Allah, I do not know what will be done with me."