ENOfficial
Jabir reported the Prophet (ﷺ) as saying, “Any slave who marries without his master's permission is a fornicator.” Tirmidhi, Abu Dawud and Darimi transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ جَابِرٌ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «أَيُّمَا عَبْدٍ تَزَوَّجَ بِغَيْرِ إِذْنِ سَيِّدِهِ فَهُوَ عَاهِرٌ» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُدَ والدرامي
sunnah.com