question #1 Sahih al-Bukhari 3011, Book 56, Hadith 220 : What are the conditions under which a person can receive a double reward according to Islamic teachings?

The Prophet (ﷺ) said, “Three persons will get their reward twice. (One is) a person who has a slave girl
and he educates her properly and teaches her good manners properly (without violence) and then
manumits and marries her. Such a person will get a double reward. (Another is) a believer from the
people of the scriptures who has been a true believer and then he believes in the Prophet (ﷺ)
(Muhammad). Such a person will get a double reward. (The third is) a slave who observes Allah’s
Rights and Obligations and is sincere to his master.”