﴿ حُرِّمَتْ عَلَيْكُمْ أُمَّهَٰتُكُمْ وَبَنَاتُكُمْ وَأَخَوَٰتُكُمْ وَعَمَّٰتُكُمْ وَخَٰلَٰتُكُمْ وَبَنَاتُ ٱلْأَخِ وَبَنَاتُ ٱلْأُخْتِ وَأُمَّهَٰتُكُمُ ٱلَّٰتِىٓ أَرْضَعْنَكُمْ وَأَخَوَٰتُكُم مِّنَ ٱلرَّضَٰعَةِ وَأُمَّهَٰتُ نِسَآئِكُمْ وَرَبَٰٓئِبُكُمُ ٱلَّٰتِى فِى حُجُورِكُم مِّن نِّسَآئِكُمُ ٱلَّٰتِى دَخَلْتُم بِهِنَّ فَإِن لَّمْ تَكُونُوا۟ دَخَلْتُم بِهِنَّ فَلَا جُنَاحَ عَلَيْكُمْ وَحَلَٰٓئِلُ أَبْنَآئِكُمُ ٱلَّذِينَ مِنْ أَصْلَٰبِكُمْ وَأَن تَجْمَعُوا۟ بَيْنَ ٱلْأُخْتَيْنِ إِلَّا مَا قَدْ سَلَفَ ۗ إِنَّ ٱللَّهَ كَانَ غَفُورًۭا رَّحِيمًۭا ﴾

“Forbidden to you are your mothers, and your daughters, and your sisters, and your aunts paternal and maternal, and a brother's daughters, and a sister's daughters; and your milk-mothers, and your milk-sisters; and the mothers of your wives; and your step-daughters - who are your foster children - born of your wives with whom you have consummated your marriage; but if you have not consummated your marriage, you will incur no sin [by marrying their daughters]; and [forbidden to you are] the spouses of the sons who have sprung from your loins; and [you are forbidden] to have two sisters [as your wives] at one and the same time - but what is past is past: for, behold, God is indeed much-forgiving, a dispenser of grace.”

Many natural desires make themselves felt in human beings—sexuality between man and woman being one of these. Islamic law, which fixes a limitation for all human emotions, has determined the limits for sexual relationships also. According to this divine dictate, only that sexual alliance between man and woman is valid which is established through a standard solemn social agreement in the form of marriage. It requires, moreover, that along with the satisfaction of natural desire, an environment of chastity must also prevail in the family life. For this purpose certain close relations have been declared prohibited to keep them beyond and above sexual desires.