The qualities that determine suitability (kafāʾa) are these:

1. Freedom from any defect that would give the spouse the right of annulment;
2. Free status—for a slave is not the equal of a free woman, and a freedman is not the equal of a woman who is free by origin;
3. Lineage—a non-Arab is not the equal of an Arab woman, nor is one who is not Qurashī the equal of a Qurashī woman, nor anyone outside the clans of Hāshim and al-Muṭṭalib the equal of their women. The sounder view is that lineage counts among non-Arabs just as it does among Arabs;
4. Chastity—an openly immoral man is not the equal of a chaste woman;
5. Occupation—the holder of a lowly trade is not the equal of one higher than he. Thus a street-sweeper, blood-letter, guard, shepherd, or bath attendant is not the equal of a tailor’s daughter; nor is a tailor the equal of a merchant’s or draper’s daughter, and neither of them is the equal of the daughter of a scholar or a judge.
   The stronger opinion is that financial means are not a separate criterion and that some qualities cannot compensate for the absence of others. A guardian may not marry his minor son to a slave woman, nor—according to the madhhab—to a woman with a bodily defect; yet, on the sounder view, he may marry him to a woman who is his inferior in the remaining qualities.

Section
A minor who is insane, and likewise an adult who is insane, is not to be married off unless there is a need, and then only to one wife. A sane minor boy, however, may be married to more than one wife. An insane person may be married off by his father or grandfather whenever a clear benefit is discerned, and the existence of need is not required, whether the intended wife is young or old, virgin or previously married. If he has neither father nor grandfather, he is not to be married while still under age; once he reaches majority, the ruler may marry him—or her—off in case of need, but not merely for some perceived advantage, according to the sounder opinion.
A person placed under interdiction for prodigality cannot contract marriage independently; he may do so only with his guardian’s permission, or the guardian may accept the contract on his behalf. If the guardian authorises him and designates a particular woman, he may not marry anyone else, and he must settle a dower equal to—or less than—the customary dower of her peers; if he stipulates more, the prevailing view is that the marriage is valid, but only up to her proper dower. If the guardian says, “Marry for one thousand,” without naming a woman, he must marry for whichever is less: one thousand or her customary dower.
If the permission is left unrestricted, the sounder view is that it is valid, and he may marry a woman suitable to him for a dower equal to that of her peers. Should the guardian himself accept the contract on the ward’s behalf, the ward’s own consent is required according to the stronger opinion; the guardian may stipulate a dower equal to, or less than, the customary amount, and if he exceeds it, the marriage is valid only up to the amount of the proper dower.