(17) The Book of the Prohibited actions
كتاب الأمور المنهي عنها
(349) Chapter: Prohibition for a Slave to run away from his Master
(349) - باب تغليظ تحريم إباق العبد من سيده
Riyad as-Salihin 1769 
Jarir bin Abdullah (May Allah be pleased with him) said:
The Prophet (ﷺ) said, "When the slave runs away from his master, his Salat (prayer) will not be accepted."

[Muslim].

Another narration is: "He is guilty of disbelief (i.e., in case he believes in the lawfulness of doing so)."

وعنه عن النبي صلى الله عليه وسلم ‏:‏ ‏"‏إذا أبق العبد، لم تقبل له صلاة ‏"‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏ ‏.‏ وفي رواية‏:‏ ‏"‏فقد كفر ‏"‏ ‏.‏
Reference : Riyad as-Salihin 1769
In-book reference : Book 17, Hadith 259