It is narrated from Hazrat Abu Musa (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Three types of people will receive a double reward. The man who has a slave girl, and he teaches her good manners and gives her the best education, then sets her free and marries her, he will receive a double reward. Similarly, the slave who fulfills the right of Allah and also fulfills the right of his master, or the person from the People of the Book who believes in his own scripture and also believes in the Shariah of Muhammad (peace and blessings be upon him), he too will receive a double reward.