Can a man marry his sister's daughter?
Fatwa No: 85322

Question

If I have right to marry with my sister's daughter.

Answer

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Marrying the sister's daughter is completely forbidden in Sharia. The evidence for this is the Holy Qur'an. Allah Says (interpretation of meaning): {Forbidden 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, …} [4: 23].
There is a consensus among all the Muslims that it is prohibited for the uncle to marry his sister's daughter.
Allah knows best.

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