Abu Dawud Book 24, Hadith Number 3922.
Chapter : Emancipation of a share in a slave.
Narated By Usamah ibn Umayr al-Huzali : (This is Abu Walid’s version): A man emancipated a share in a slave and the matter was mentioned to the Prophet (PBUH). He said: Allah has no partner.
Ibn Kathir added in his version: The Prophet (PBUH) allowed his emancipation.