Musnad Ahmad 27:142

Sufyan narrated to us, from ‘Amr, from Salim, from his father, attributing it to the Prophet, may Allah bless him and grant him peace: "If a slave is between two [owners], and one of them emancipates his share, then if he is wealthy, the value [of the slave] is assessed upon him—neither at a loss nor at an excess—then he is emancipated."