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. (Using translation from Abū Dāʾūd 2079)
النَّبِيِّ ﷺ قَالَ إِذَا نَكَحَ الْعَبْدُ بِغَيْرِ إِذْنِ مَوْلَاهُ فَنِكَاحُهُ بَاطِلٌ