Musannaf Ibn Abi Shayba 26:397

Ibn ‘Ulayyah narrated to us, from Ibn ‘Awn, from al-Sha’bi, who said: Wealth belonging to some people was brought to Ibn Mas’ud. They had emancipated him as a *sa’ibah* (a pre-Islamic form of manumission where the master renounces all rights to the slave). He said to his (the slave’s) masters, "This is the wealth of your freedman." They said, "We have no need for it, for we had emancipated him as a *sa’ibah*." Ibn Mas’ud said, "Indeed, there is a place for it in the wealth of the Muslims."