Because they are among those capable of articulating the contract, and their expression within it is valid. For this reason, their acceptance of marriage for themselves is valid, and they were only deprived of the guardianship itself because it requires perfection, while there is no need for that in merely articulating it. As for if the husband appoints him as an agent to accept marriage on his behalf, or the father appoints him as an agent to accept marriage for his young son, our companions stated: It is not valid, because he is one of the two parties to the contract, so his appointment is not permissible just as in the offer (ijab). It is possible that the appointment of those we have mentioned is valid because they are among those qualified for it, and their acceptance of marriage for themselves is valid, so it is permissible for them to act as deputies in it for others, like in a sale. This is one of the two opinions of the companions of al-Shafi'i regarding the slave (28).

1110 - Issue: He said: (The slave woman of a woman may be married off by whoever marries her off, with her permission.)

There is a difference in the narration from Ahmad regarding who marries off a woman's slave. It was reported from him that the marriage is under the authority of [the guardian of her mistress] (1). Al-Qadi said: This is the correct view. It is also the school of al-Shafi'i, because the implication of the evidence is that the guardianship belongs to her, but it is prohibited for her to exercise it personally due to her deficiency; thus, it is established for her guardians, just like the guardianship over her own self. Furthermore, they would be her guardians if she were manumitted, so in her state of bondage, they are even more deserving. Then, if her mistress is discerning (rashida), it is not permissible to marry off her slave woman except with her permission, because she is her property, and it is not permitted to dispose of the property of a discerning person without their permission. Her verbal declaration of that is considered, even if she is a virgin, because her silence is only sufficient in marrying off her own self due to her shyness, and she would not be shy about marrying off her slave woman. If she is young, insane, or a spendthrift (safihah), then her guardian has guardianship over her property, so he may marry off her slave woman if there is an advantage (haz) in marrying her off; otherwise, he does not have the authority to marry her off. The same ruling applies to the slave woman of his young son (2). Some Shafi'is said: He does not have the right to marry her off under any circumstances, because it involves placing the property of the young girl at risk (3), for she might become pregnant and perish. Our position is that he has the right to manage her property in whatever includes an advantage, and marrying her off here involves an advantage because it is a matter of speech; thus it is permissible, like all other permissible transactions.