Source: Fatāwā Amunpuri by Shaykh Ghulam Mustafa Zaheer Amunpuri
❖ Question:
What is the ruling if someone marries his wife’s real (biological) sister while the wife is still present (in the marriage)?
✿ Answer:
It is not permissible to marry the real sister of one’s wife while the wife is still in the marriage.
Such a marriage is invalid and void — it does not come into effect at all.
Doing so is considered fornication (zinā) in Islamic law.
Allah ﷻ says:
﴿ وَأَنْ تَجْمَعُوا بَيْنَ الْأُخْتَيْنِ ﴾
📚 [Sūrat al-Nisā’: 23]
“And (also forbidden is) that you combine two sisters (in marriage at the same time).”
✔ Summary:
① Marrying a woman and her sister simultaneously is haram (forbidden).
② The second nikāḥ does not take place — it is invalid (bāṭil).
③ Such an act is not considered marriage but zinā under Islamic law.
