Hurrimat AAalaykum ommahatukum wabanatukum waakhawatukum waAAammatukum wakhalatukum wabanatu al-akhi wabanatu al-okhti waommahatukumu (surah Nisa: 23)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(4:23) Forbidden to you are your mothers, *34 your daughters, *35 your sisters, *36 your father's sisters and your mother's sisters, your brother's daughters and your sister's daughters, *37 your milk-mothers, your milk-sisters, *38 the mothers of your wives, *39 and the stepdaughters - who are your foster-children, *40 born of your wives with whom you have consummated the marriage; but if you have not consummated the marriage with them, there will be no blame upon you (if you marry their daughters).

It is also forbidden for you to take the wives of the sons who have sprung from your loins *41 and to take two sisters together in marriage, *42 although what is past is past. Surely Allah is All-Forgiving, All-Compassionate. *43

Hurrimat `alaikum umma haatukum wa bannaatukum wa akhawaatukum wa `ammaatukum wa khaalaatukum wa banaatul akhi wa banaatul ukhti wa ummahaatu kumul laateee arda` nakum wa akhawaatukum minarradaa`ati wa ummahaatu nisaaa`ikum wa rabaaa`i bukumul laatee fee hujoorikum min nisaaa`ikumul laatee dakhaltum bihinna Fa il lam takoonoo dakhaltum bihina falaa junaaha `alaikum wa halaaa`ilu abnaaa`ikumul lazeena min aslaabikum wa an tajma`oo bainal ukhtaini illaa maa qad salaf; innallaaha kaana Ghafoorar Raheema

*34). The word 'mother' applies to one's step-mother as well as to one's real mother. Hence the prohibition extends to both. This injunction also includes prohibition of the grandmother, both paternal and maternal. There is disagreement on whether a woman with whom a father has had an unlawful sexual relationship is prohibited to his son or not. There are some among the early authorities who do not believe in such prohibition. But there are others who go so far as to say that a woman whom a father has touched with sexual desire becomes prohibited to the son. Likewise, there is disagreement among the scholars of the early period of Islam in regard to a woman with whom a person has had an illegitimate sexual relationship whether she is prohibited to his father or not. In the same way there has been disagreement in regard to a man with whom a mother or daughter has had an illegitimate sexual relationship, whether or not marriage with him is prohibited for both the mother and daughter. (See Jassas, vol. 2, pp. 113 ff., and Bidayat al-Mujtahid, vol. 2, pp. 33 f. - Ed.) There is a great deal of formal, legal discussion on this point. But even a little reflection makes it evident that if a man marries a woman who is at once the object of the desire of either his father or his son, and if a man marries a woman and is attracted to either her mother or daughter, this militates against the requirements of a righteous society. The spirit of the Law is opposed to the legal hair-splitting which makes a distinction between sexual relations that take place either within the marital framework or outside it, and between either touching or looking with desire and so on. The plain fact is that if the sexual passions of both the father and the son are focused on the same woman, or conversely, if the sexual passions of both the mother and daughter are focused on the same man, this situation is full of evil and mischief for family life and the Law can never tolerate it. The Prophet (peace be on him) has said: 'Whoever looks at the genitals of a woman, both the mother and daughter of that woman become prohibited for him.' In another tradition, the Prophet (peace-be on him) said: 'God will not even care to look at the person who casts his look at the genitals of a woman as well as those of her daughter.' (Jassas, Ahkam al-Qur'an, vol. IV, p. 141.) These traditions bring out the intent of the Law very clearly.
*35). The injunction with regard to daughters applies to grand-daughters on both the paternal and maternal sides as well. There is disagreement, however, whether a daughter born of an illegitimate relationship becomes prohibited or not. According to Abu Hanifah, Malik and Ahmad b. Hanbal such a daughter is prohibited in the same way as a daughter born in wedlock; Shafi'i, however, is of the opinion that such daughters are not prohibited. The very idea, however, of marrying a girl who was born of one's own semen would be repulsive to any decent person.
*36). This applies to full sisters as well as to half-sisters.
*37). In all these relationships, no distinction is made between the full and step-relationships. The sister of a man's father or mother, whether full sister or step-sister, is prohibited to him. Likewise, the daughters of a man's brothers and sisters are prohibited just as if they were one's own daughters. (See Bidayat al-Mujtahid, vol. 2, pp. 31 ff. - Ed.)
*38). There is consensus among Muslims that if a boy or girl is breast-fed by a woman, that woman attains the status of mother, and her husband the status of father. It is forbidden to marry relatives through milk where the degree of relationship is such as /to constitute a bar to marriage in the case of blood-relations. The basis of this rule is the saying of the Prophet (peace be on him): 'Whatever is rendered prohibited by descent (nasab) is likewise rendered prohibited by breast-feeding.' (Bukhari, 'Shahadat', 4, 7,13,14; Muslim, 'Rida'ah', 1-14,26-30; etc. - Ed.) According to Abu Hanifah and Malik prohibition is established if a child suckles milk from a woman's breast equal to that minimum quantity which nullifies fasting. But according to Ahmad b. Hanbal, it is established by three sucklings; and according to Shafi'i by five. There is also disagreement about the maximum age up to which breast-feeding leads to prohibition of marriage with the woman concerned. In this connection, jurists have expressed the following opinions:
(1) Suckling is of legal significance only when it occurs before a child has been weaned, and when milk is its main source of nourishment. If a child suckles from a woman's breast after having been weaned, this is legally no different from drinking anything else. This is the opinion of Umm Salamah and Ibn 'Abbas, and a tradition to this effect has also been reported from 'Ali. This is also the view of al-Zuhri, Hasan al-Basri, Qatadah, 'Ikrimah and Awza'i.
(2) Prohibition is established by breast-feeding during the first two years of a child's life. This is the view of 'Umar, Ibn Mas'ud, Abu Hurayrah and 'Abd Allah b. 'Umar. Among jurists, Shafi'i, Ahmad b. Hanbal, Abu Yusuf, Muhammad b. al-Hasan al-Shaybani and Sufyan al-Thawri followed this view; and according to a report, so did Abu Hanifah. Malik largely followed this view, but he was of the opinion that if breast-feeding took place a month or two after the age of two, the prohibition would still remain in effect.
(3) The generally-reported opinion of Abu Hanifah and Zufar is that a bar to marriage is created by breast-feeding up to an age limit of two and a half years.
(4) Some other jurists are of the opinion that the prohibition comes into effect irrespective of the age when breast-feeding takes place. This opinion is based on the view that the effective cause of the prohibition is a woman's milk, rather than the age of the person fed. Hence, even in the case of an older person, the same prohibition would apply as in the case of an infant. This is the view of 'A'ishah and this has been supported on the basis of a tradition from 'Ali, which is presumably .authentic. Among the jurists this opinion has been followed by 'Urwah b. al-Zubayr, 'Ata', Layth b. Sa'd and Ibn Hazm. (On this subject see Jassas, vol. 2, pp. 124 ff.; and Ibn Rushd, Biddyat al-Mujtahid, vol. 2,'pp'. 35 ff. -Ed.)
*39). There is disagreement about prohibition in respect of the mother of the woman with whom one has merely contracted marriage (without having consummated it). Abu Hanifah, Malik, Ahmad b. Hanbal and Shafi'i believe that such a relationship is prohibited. 'Ali, however, holds the opinion that unless the marriage has been consummated the mother of one's wife does not become prohibited.
*40). The prohibitive restriction in regard to such girls is not based on the consideration of their having been brought up in the house of a step-father. The reference to the child's upbringing in his house points to the delicacy of this relationship. The jurists are almost unanimous that it is prohibited to marry one's step-daughter irrespective of whether or not she has been raised in the step-father's house.
*41). This restriction has been added because the widow of one's adopted son is, according to Islam, not prohibited. It is only the wife of one's own son who is prohibited. Likewise, the wives of grandsons (paternal and maternal) are prohibited to grandfathers (on both the mother's and father's side).
*42). The Prophet (peace be on him) has taught that it is prohibited for a man to combine in marriage an aunt - whether maternal or paternal - with her niece. The guiding principle is that it is prohibited to have as wives two women who, if one were male, would be prohibited to each other. (See Bidayat al-Mujtahid, vol. 2, p. 41 - Ed.)
*43). This is an assurance that God would not call them to task for such misdeeds of the Jahiliyah period as combining two sisters in matrimony, provided they abstained from doing so in the future. (See also n. 32 above.) For this reason a man with two sisters as his wives is required to divorce one of them when he embraces Islam.