Al-Hāfidh Ibn Hajr (rahimahullāh) said:
990: Narrated Jābir (radiyallāhu ‘anhu): Allah’s Messenger (salallāhu ‘alaihi wasallam) said:
“Any servant who marries without the permission of his master or his people is a fornicator.”
Ibn Hajr said: Reported by Ahmad, Abu Dawud, An-Nasā’i, At-Tirmidhi who authenticated it, likewise Ibn Hibbān.
(Ahmad, no. 14212. Abu Dawud, no. 2078. At-Tirmidhī, no. 111. It is not reported by An-Nasaa’ee nor Ibn Hibbān. Al-Hafidh (Ibn Hajr) himself did not in “It-hāf al-Mahrah” (3/215) ascribe it/give it support to Ibn Hibbaan. Its chain of narration is weak.)
Shaikh Sālih al-Fawzān (hafidhahullāh) said:
This also is an invalid marriage, that an owned (enslaved) person should marry without the permission of his master. That is because the owned person belongs to his master. So it is not permitted for him to marry, or to sell, or to buy, or to exchange a thing except with the permission of his master. And if he were to marry without the permission of his master, then the marriage would be invalid – and if he were to marry with the permission of his master, then the marriage is valid.
Adapted from volume 4, no. 990 (Eng. 843): Kitābun-Nikāh (The Book of Marriage) from Shaikh Sālih al-Fawzān’s explanation of Bulūgh Al-Marām min Adillatil-Ahkām of Al-Hāfidh Ahmad Ibn ‘Ali Ibn Hajr Al-Asqalāni (born 773H, died 852H), entitled Tas-heel al-Ilmām bi-fiqhil-Ahādeeth min Bulūghil-Marām and is printed in seven volumes.