Musnad Ahmad 25:364

Yunus narrated to us, Abu 'Awanah narrated to us, from Simak, from Sa'id ibn Jubayr, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) met Ma'iz ibn Malik and said: "Is it true what has reached me about you?" He said: "And what has reached you about me?" He said: "It has reached me that you committed adultery with the slave-girl of the family of so-and-so." He said: "Yes." So he turned him away until he had testified four times, then he ordered that he be stoned.