Nikah with the Daughter of One's Sister's Son

Question

For what reason is nikah with the daughter of one's sister's son haram, and where is the proof of this?

Answer

It is forbidden on account of the prohibition by kinship: [ar]فتحرم بنات الإخوة والأخوات وبنات أولاد الإخوة والأخوات وإن نزلن[/ar] “Forbidden are the daughters of brothers and sisters and the daughters of the children of brothers and sisters, however far down they descend” (“Shami”, vol. 1, Fasl al-Muharramat).

Source: Fatawa Mahmudiyya

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