Sunan an-Nasa'i 3218
Narrated Abu Hurairah:
It was narrated from Abu Hurairah that the Messenger of Allah said: "There are three who are promised the help of Allah: The Mukatab who wants to buy his freedom, the one who gets married seeking to keep himself chaste, and the Mujahid who fights in the cause of Allah."

*Mukatab: the slave who has made a contract of manumission.
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ مُحَمَّدِ بْنِ عَجْلاَنَ، عَنْ سَعِيدٍ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏
"‏ ثَلاَثَةٌ حَقٌّ عَلَى اللَّهِ عَزَّ وَجَلَّ عَوْنُهُمُ الْمُكَاتَبُ الَّذِي يُرِيدُ الأَدَاءَ وَالنَّاكِحُ الَّذِي يُرِيدُ الْعَفَافَ وَالْمُجَاهِدُ فِي سَبِيلِ اللَّهِ ‏"‏ ‏.‏