Ata bin Abi Rabah, Abu al-Zubayr and Amr bin Dinar (may Allah have mercy on them) narrated that Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) told them that a man of the Ansar freed his slave (on the condition that he would be free) if something happened to him and he died. The Prophet (peace and blessings be upon him) sent for the slave and sold him to Nu'aym bin Abdullah (may Allah be pleased with him), one of Banu Adi bin Ka'b.
His words "if something happened to him and he died" are part of the condition of manumission, not a report of the death of the one who freed him. It is from here that some narrators erred in mentioning the man's death at the time of the sale; his death was mentioned only within the condition of manumission on the day of the tadbir, and this is what the narration of the majority indicates.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المدبر / 21548