Musnad Ahmad 790:194

Yahya ibn Hammad narrated to us, Abu 'Awanah narrated to us, from Simak ibn Harb, from al-Hasan al-Basri, from 'Imran ibn Husayn, that a man emancipated six slaves of his at the time of his death. His heirs from the Bedouins came and informed the Messenger of Allah, peace and blessings of Allah be upon him, of what he had done. He said: "Did he do that?" They said: "Had we known, if Allah wills, we would not have prayed over him." He said: So he drew lots among them, and he emancipated two of them and returned four to slavery.