Imran bin Umayr narrates from his father, who was the slave of Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), that Sayyiduna Abdullah (may Allah be pleased with him) said to him: O Umayr! What property do you have? I intend to free you, for I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever frees a slave, the slave's property belongs to the one who freed him."
Imran bin Umayr narrates from his father that Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) freed his father Umayr, then said: Your property is mine; then he left it to him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10773