Abdullah narrated that the Prophet said: "Whichever slave gets married without the permission of his owner, then he is a fornicator." (Using translation from Tirmidhī 1112)
عَنِ النَّبِيِّ ﷺ قَالَ «أَيُّمَا عَبْدٍ تَزَوَّجَ بِغَيْرِ إِذْنِ مَوَالِيهِ فَهُوَ زَانٍ»