Musnad Abu Ya'la al-Mawsili 109:257

Abu Khaythama narrated to us, Abd al-Samad narrated to us, my father narrated to us, al-Qasim ibn Abd al-Wahid al-Makki narrated to us, Abdullah ibn Muhammad ibn Aqil narrated to us, he said: I heard Jabir saying: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, when a slave marries without the permission of his master, he is an adulterer (or a fornicator)."