Musannaf Ibn Abi Shayba 35:37

Ibn ‘Ulayyah narrated to us, from Ayyub, from Abu Qilabah, from Abu al-Muhallab, from ‘Imran ibn Husayn, that a man had six slaves and he emancipated them at the time of his death. The Prophet, peace and blessings of Allah be upon him, drew lots among them, so he emancipated two and kept four in slavery.