It was narrated that Jabir bin 'Abdullah said:
"A man among us promised freedom to a slave after his death, and he did not have any property other than him (this slave). So the Prophet (ﷺ) sold him, and Ibn (Nahham), a man from Banu 'Adi, bought him." (ID)
English reference (ID): Vol. 3, Book 19, Hadith 2513 (ID)
Arabic reference (ID): Book 19, Hadith 2609 (ID)