Sahih al-Bukhari 3446
صحيح البخاري#3446SahihNarrated Abu Musa Al-Ash`ari:Allah's Messenger (ﷺ) said, "If a person teaches his slave girl good manners properly, educates her properly, and then manumits and marries her, he will get a double reward. And if a man believes in Jesus and then believes in me, he will get a double reward. And if a slave fears his Lord (i.e. Allah) and obeys his masters, he too will get a double reward
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 60:116