Musnad Ahmad 1131:1

Ya'qub narrated to us, 'Abd al-'Aziz ibn al-Muttalib informed us, from Sa'id ibn 'Amr ibn Sharhabil, from his grandfather, who said: A book I found among the books of Sa'id ibn Sa'd ibn 'Ubadah: That 'Umarah ibn Hazm testified: "That the Messenger of Allah, peace and blessings of Allah be upon him, judged by the oath along with the witness." Zayd ibn al-Hubab said: I asked Malik ibn Anas about the oath and the witness: Is it permissible in divorce and manumission? He said: "No, this is only in buying and selling and things similar to it."