A man is forbidden, by the Ḳur-án[257] and the Sunneh, to marry his mother, or other ascendant; daughter, or other descendant; his sister, or half sister; the sister of his father or mother, or other ascendant; his niece, or any of her descendants; his foster-mother who has suckled him five times in the course of the first two years, or a woman related to him by milk in any of the degrees which would preclude his marriage with her if she were similarly related to him by consanguinity; the mother of his wife; the daughter of his wife, in certain conditions; his father's wife, and his son's wife; and to have at the same time two wives who are sisters, or aunt and niece: he is forbidden also to marry his unemancipated slave, or another man's slave, if he has already a free wife; and to marry any woman but one of his own faith, or a Christian, or a Jewess. A Mohammadan woman, however, may only marry a man of her own faith. An unlawful liaison with any woman prevents a man from marrying any of her relations who would be forbidden to him if she were his wife. A cousin (the daughter of a paternal uncle) is often chosen as a wife, on account of the tie of blood which is likely to attach her more strongly to her husband, or on account of an affection conceived in early years. Parity of rank is generally much regarded; and a man is often unable to obtain as his wife the daughter of one of a different profession or trade, unless an inferior; or a younger daughter when an elder remains unmarried. A girl is often married at the age of twelve years, and sometimes at ten, or even nine: the usual period is between twelve and sixteen years. At the age of thirteen or fourteen she may be a mother. The young men marry a few years later. The most important requisite in a wife is religion. The Prophet said, "A virtuous wife is better than the world and all that it contains." "A virtuous wife," said Luḳmán, "is like a crown on the head of a king; and a wicked wife is like a heavy burden on the back of an old man." Among the other chief requisites are agreeableness of temper, beauty of form (undiminished by any defect or irregularity of features or members), moderation in the amount of dowry required, and good birth. It is said, "If thou marry not a virgin [which is most desirable], marry a divorced woman, and not a widow; for the divorced woman will respect thy words when thou sayest, 'If there were any good in thee thou hadst not been divorced;' whereas the widow will say, 'May God have mercy on such a one [her first husband]! he hath left me to one unsuited to me.'" But according to another selfish maxim, the woman most to be avoided is she who is divorced from a man by whom she has had a child; for her heart is with him, and she is an enemy to the man who marries her after.[258]