Sahih Muslim
The Book of Oaths (Kitab Al-Aiman)
Book Number: 015 / Hadith Number: 4112
'Imran b. Husain reported that a person who had no other property emancipated six slaves of his at the time of his death. Allah's Messenger (may peace be upon him) called for them and divided them into three sections, cast lots amongst them, and set two free and kept four in slavery; and he (the Holy Prophet) spoke severely of him.