When one of the two mukatabs purchases the other, his purchase is valid, as is his ownership, because the legal disposal was issued by a person qualified to perform it regarding its proper object. It is the same whether they are both mukatabs of one master or of two masters. If the second returns and purchases the one who had purchased him, it is not valid, because he [the first] is his master and owner, and it is not permitted for the owned to own his master, for this would lead to a contradiction of legal rulings. Each one of them would be saying to the other: "I am your master, and I have a right over you to the wealth of the kitaba, which you must pay to me, and if you are unable, I have the right to annul your kitaba and return you to being a slave for me." This is a contradiction. Since it is considered impossible for a woman to own her husband through ownership by right of hand [mil al-yamin] because of the husband's established ownership over her through the marriage contract, it is more appropriate here. Furthermore, if this were valid, the two debts would offset each other if they were equal, and both would be emancipated simultaneously. Once this is established, the purchase of the first is valid, and the one sold among them remains in his state of kitaba; if he pays, he is emancipated, and his wala' [right of patronage] is suspended. If his master pays his kitaba, he belongs to him [the master], because he was emancipated by his payment to him. If he is unable to perform, his wala' belongs to his master, because the slave cannot have wala' established for him, and because the master takes his wealth, so he takes his rights as well. This is the requirement of the statement of the Qadi, while the requirement of the statement of Abu Bakr is that the wala' belongs to his master, because the mukatab is a slave for whom wala' cannot be established, so it is established for his master. They mentioned this regarding the case where one emancipates with the permission of his master, or one writes a contract of kitaba with his slave and he pays his kitaba; this is similar to that. It is possible that a distinction is made between the two, because the emancipation was completed with the master's permission, so the beneficence [in'am] is achieved from him by his permission. Here, it does not require his permission, so there is no beneficence from him upon him, and thus he has no wala' over him, unless his master renders him unable to perform. And Allah knows best.

Section: If the prior one among them is not known, Abu Bakr said: Both sales are void, and each one of them is returned to his kitaba, because the validity of the sale of each one is doubtful, so it is returned to certainty.