"(We also sent) Lut (as a messenger): behold, He said to his people, "Do ye do what is shameful though ye see (its iniquity)? Would ye really approach men in your lusts rather than women? Nay, ye are a people (grossly) ignorant! But his people gave no other answer but this: they said, "Drive out the followers of Lut from your city: these are indeed men who want to be clean and pure!" Then We saved him and his household save his wife; We destined her to be of those who stayed behind. And We rained down on them a shower (of brimstone): and evil was the shower on those who were admonished (but heeded not)! - Quran 27:54 (read more)

"Narrated Kurib: the freed slave of Ibn 'Abbas, that Maimuna bint Al-Harith told him that she manumitted a slave-girl without taking the permission of the Prophet. On the day when it was her turn to be with the Prophet, she said, "Do you know, O Allah's Apostle, that I have manumitted my slave-girl?" He said, "Have you really?" She replied in the affirmative. He said, "You would have got more reward if you had given her (i.e. the slave-girl) to one of your maternal uncles." - Sahih Bukhari 3:47:765 (read more)

"Mohammed had many male and female slaves. He used to buy and sell them, but he purchased more slaves than he sold, especially after God empowered him by His message, as well as after his immigration from Mecca. He once sold one black slave for two. His name was Jacob al-Mudbir. His purchases of slaves were more than he sold. He was used to renting out and hiring many slaves, but he hired more slaves than he rented out." - Ibn Qayyim al-Jawziyya