Is the purchase of a Muslim slave by an infidel valid if the slave is a relative of the infidel whom the infidel is forbidden to own (e.g., father or brother)?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
The purchase of a Muslim slave by an infidel, where the slave is a relative upon whom ownership is forbidden (such as a father or brother), is valid, leading to the immediate emancipation of the slave, according to some of our companions. This ruling is supported by the reasoning that the prohibition against ownership is temporary, and the benefit derived from immediate freedom far outweighs the momentary indignity of ownership by the infidel. This situation is differentiated from cases where ownership does not immediately cease, such as purchasing a relative the infidel is generally forbidden to own or purchasing game by one in the state of Ihram (sacred state for Hajj/Umrah), where ownership would otherwise remain.
Supporting text
One opinion among our companions, narrated by Abu Al-Khattab as one of two narrations, holds that such a purchase is invalid. This is reasoned because it is a purchase resulting in ownership of a Muslim, which is prohibited, similar to purchasing a slave upon whom emancipation is not obligatory immediately upon purchase. Furthermore, what is prohibited in purchase remains prohibited even if ownership is immediately nullified afterward, analogous to a person in Ihram purchasing game.