Among the conditions of marriage: the presence of a guardian.

The Shaykh : Among the important conditions is the guardian, because the Prophet (peace and blessings be upon him) said: If a woman, who is sane and prudent, marries herself off, the marriage is not valid. If she sold her house, what would happen? The sale is valid. Why? Because marriage is a serious contract, and a woman is mentally limited; she may look at the near one and not the far one. Her guardian is undoubtedly more discerning and precise in his judgment than she is. Therefore, a guardian is necessary; a guardian is necessary. They are ranked: the first, and the most entitled, is the father, however high up the lineage he may be; then the son, however low down the lineage he may be; then the full brother and his sons; then the paternal half-brother and his sons, but the paternal half-brother takes precedence over the sons of the full brother; then the full paternal uncle and his sons; then the paternal half-uncle and his sons. Do maternal half-siblings have guardianship in marriage? No, a maternal half-brother has no guardianship, even if no asabah (residuary male heirs) are present. The judge will marry her off, not the maternal half-brother. If a woman has only a maternal half-brother and no asabah, and she proposes to her maternal half-brother, who will marry her? The judge will marry her. To whom is the proposal currently directed? To the maternal half-brother, because he is a relative, but he has no guardianship in marriage. The judge will marry her. So, who are the guardians of a woman in marriage? We say: her guardians are the asabah. There is no right for one with a fixed share, nor for one with a kinship tie, in the guardianship of marriage; it is only for the asabah. Their order is to begin with the ancestors, then the descendants, then the brothers and their sons, then the uncles and their sons.