Three kinds of people will have a double reward: A man from the People of the Scripture (Jews or Christians) who believed in his prophet and (also) believed in Muhammad; a slave who fulfills his duties towards Allah and towards his master; and a man who owned a slave-girl, so he disciplined her well and educated her well then freed her and married her. He will receive a double reward. [Al-Bukhari and Muslim]

«ثلاثة لهم أجران: رجل من أهل الكتاب آمن بنبيه، وآمن بمحمد، والعبد المملوك إذا أدى حق الله، وحق مواليه، ورجل كانت له أمة فأدبها فأحسن تأديبها، وعلمها فأحسن تعليمها، ثم أعتقها فتزوجها؛ فله أجران». [متفق عليه]