وَكَيْفَ تَأْخُذُونَهُ وَقَدْ أَفْضَى بَعْضُكُمْ إِلَى بَعْضٍ وَأَخَذْنَ مِنْكُمْ مِيثَاقًا غَلِيظًا ﴿۲۱﴾ وَلَا تَنْكِحُوا مَا نَكَحَ آبَاؤُكُمْ مِنَ النِّسَاءِ إِلَّا مَا قَدْ سَلَفَ إِنَّهُ كَانَ فَاحِشَةً وَمَقْتًا وَسَاءَ سَبِيلًا ﴿۲۲﴾ حُرِّمَتْ عَلَيْكُمْ أُمَّهَاتُكُمْ وَبَنَاتُكُمْ وَأَخَوَاتُكُمْ وَعَمَّاتُكُمْ وَخَالَاتُكُمْ وَبَنَاتُ الْأَخِ وَبَنَاتُ الْأُخْتِ وَأُمَّهَاتُكُمُ اللَّاتِي أَرْضَعْنَكُمْ وَأَخَوَاتُكُمْ مِنَ الرَّضَاعَةِ وَأُمَّهَاتُ نِسَائِكُمْ وَرَبَائِبُكُمُ اللَّاتِي فِي حُجُورِكُمْ مِنْ نِسَائِكُمُ اللَّاتِي دَخَلْتُمْ بِهِنَّ فَإِنْ لَمْ تَكُونُوا دَخَلْتُمْ بِهِنَّ فَلَا جُنَاحَ عَلَيْكُمْ وَحَلَائِلُ أَبْنَائِكُمُ الَّذِينَ مِنْ أَصْلَابِكُمْ وَأَنْ تَجْمَعُوا بَيْنَ الْأُخْتَيْنِ إِلَّا مَا قَدْ سَلَفَ إِنَّ اللَّهَ كَانَ غَفُورًا رَحِيمًا ﴿۲۳﴾

﴾21﴿ Wa kaifa ta'khuzoonahoo wa qad afdaa ba'dukum ilaa ba'dinw wa akhazna minkum meesaaqan ghaleezaa
﴾22﴿ Wa laa tankihoo maa nakaha aabaaa'ukum minan nisaaa'i illaa maa qad salaf; innahoo kaana faahishatanw wa maqtanw wa saaa'a sabeelaa
﴾23﴿ Hurrimat 'alaikum umma haatukum wa banaatukum 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 bihinna 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

﴾21﴿ And how can you take it back, when you have been intimately joined with one another, and they have taken from you a firm covenant?
And do not marry those women whom your fathers have married, except for what has already passed. Surely that is an obvious sin, and a cause of Allah’s anger, and an evil way.
﴾22﴿ And do not marry women whom your fathers have married, except for what has already passed; surely that is a clear sin, a cause of Allah’s anger, and an evil way.
﴾23﴿ Forbidden to you (for marriage) are: your mothers, your daughters, your sisters, your paternal aunts, your maternal aunts, the daughters of your brothers, the daughters of your sisters, your foster mothers who nursed you, your foster sisters, the mothers of your wives (mothers-in-law), and your stepdaughters under your care, born of your wives with whom you have consummated marriage; but if you have not consummated with them, then there is no blame upon you. And (also forbidden are) the wives of your sons who are from your own loins, and that you take two sisters together in marriage—except for what has already passed; surely Allah is All-Forgiving, Most Merciful.

[21] In this verse is proof that once a husband and wife have come together, the full dowry becomes obligatory.
And by “firm covenant (mithāq),” what is meant is the bond of marriage itself.
[22] This ruling prohibits marriage with one’s stepmother—something that was considered permissible in the Age of Ignorance, as mentioned in “what has already passed” (مَا قَدْ سَلَفَ).
(Question) “Do not marry” (لَا تَنْكِحُوا) is for the future, while “what has already passed” refers to the past; so, how is this exception correct?
(Answer) “Except” (إِلَّا) here means “however” (but), which is a disconnected exception, or it can mean “after this.”
[23] This is the eleventh ruling: it details those women who are permanently forbidden for marriage.
Seven of these are by blood relation, and this includes grandmothers and granddaughters as well.
Two are by cause (marriage ties), and two are by suckling (foster relations); however, according to the hadith, those relations that are forbidden by blood are also forbidden by fosterage.
There are four categories forbidden due to in-law relations. Although the people of the Age of Ignorance accepted these prohibitions, some of them considered certain cases to be lawful. This is referenced by the phrase "except for what has already passed" (إِلَّا مَا قَدْ سَلَفَ).