It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that a man freed his six slaves at the time of his death, and he had no wealth other than them. This reached the Prophet (peace and blessings be upon him), "so he (peace and blessings be upon him) spoke severely to the man, then called them, divided them into three parts, then cast lots between them, freed two and kept four in slavery."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15548