Surah Al-Ahzab, ayah 4

33:4

مَّا جَعَلَ ٱللَّهُ لِرَجُلٖ مِّن قَلۡبَيۡنِ فِي جَوۡفِهِۦۚ وَمَا جَعَلَ أَزۡوَٰجَكُمُ ٱلَّٰٓـِٔي تُظَٰهِرُونَ مِنۡهُنَّ أُمَّهَٰتِكُمۡۚ وَمَا جَعَلَ أَدۡعِيَآءَكُمۡ أَبۡنَآءَكُمۡۚ ذَٰلِكُمۡ قَوۡلُكُم بِأَفۡوَٰهِكُمۡۖ وَٱللَّهُ يَقُولُ ٱلۡحَقَّ وَهُوَ يَهۡدِي ٱلسَّبِيلَ ٤

Mmā ja'alallāhu lirajulim min qalbayni fī jawfihī wamā ja'ala azwājakumul-lā'ī tuzāhirūna minhunna ummahātikum wamā ja'ala ad'iyā'akum abnā'akum dhālikum qawlukum bi afwāhikum wallāhu yaqūlul-haqqa wahuwa yahdis-sabīl

Allāh has not made for a man two hearts in his interior. And He has not made your wives whom you declare unlawful1180 your mothers. And He has not made your claimed [i.e., adopted] sons your [true] sons. That is [merely] your saying by your mouths, but Allāh says the truth, and He guides to the [right] way.

Footnotes

1180 By the expression "You are to me like the back of my mother." Such an oath taken against approaching one's wife was a pre-Islāmic practice declared by Allāh (subḥānahu wa taʿālā) to be a sin requiring expiation as described in 58:3-4.