(17) باب فِي نِكَاحِ الْعَبْدِ بِغَيْرِ إِذْنِ مَوَالِيهِ
Ibn 'Umar reported the Prophet (ﷺ) as saying "If a slave marries without the permission of his master, his marriage is null and void.Abu Dawud said "This tradition is weak. This is mauquf(does not go back to the Prophet). This is the statement of the Ibn 'Umar himself.
Reference: Sunan Abi Dawud 2079
In-book reference: Book 12, Hadith 34
English translation: Book 11, Hadith 2074