Musnad Ahmad 790:136

Hashim narrated to us, Mubarak narrated to us, from al-Hasan, who said: Imran ibn Husayn narrated to me, saying: A man was brought who had emancipated six slaves at the time of his death, and he had no wealth other than them. The Prophet, peace and blessings of Allah be upon him, drew lots among them, so he emancipated two and kept four in servitude.