An-Nisa 4:23

حُرِّمَتۡ عَلَيۡكُمۡ أُمَّهَٰتُكُمۡ وَبَنَاتُكُمۡ وَأَخَوَٰتُكُمۡ وَعَمَّـٰتُكُمۡ وَخَٰلَٰتُكُمۡ وَبَنَاتُ ٱلۡأَخِ وَبَنَاتُ ٱلۡأُخۡتِ وَأُمَّهَٰتُكُمُ ٱلَّـٰتِيٓ أَرۡضَعۡنَكُمۡ وَأَخَوَٰتُكُم مِّنَ ٱلرَّضَٰعَةِ وَأُمَّهَٰتُ نِسَآئِكُمۡ وَرَبَـٰٓئِبُكُمُ ٱلَّـٰتِي فِي حُجُورِكُم مِّن نِّسَآئِكُمُ ٱلَّـٰتِي دَخَلۡتُم بِهِنَّ فَإِن لَّمۡ تَكُونُواْ دَخَلۡتُم بِهِنَّ فَلَا جُنَاحَ عَلَيۡكُمۡ وَحَلَـٰٓئِلُ أَبۡنَآئِكُمُ ٱلَّذِينَ مِنۡ أَصۡلَٰبِكُمۡ وَأَن تَجۡمَعُواْ بَيۡنَ ٱلۡأُخۡتَيۡنِ إِلَّا مَا قَدۡ سَلَفَۗ إِنَّ ٱللَّهَ كَانَ غَفُورٗا رَّحِيمٗا 23

Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father's sisters, your mother's sisters, your brother's daughters, your sister's daughters, your [milk] mothers who nursed you, your sisters through nursing, your wives' mothers, and your step-daughters under your guardianship [born] of your wives unto whom you have gone in. But if you have not gone in unto them, there is no sin upon you. And [also prohibited are] the wives of your sons who are from your [own] loins, and that you take [in marriage] two sisters simultaneously, except for what has already occurred. Indeed, Allah is ever Forgiving and Merciful