Is Marriage with a Foster Sister Permissible? A Qurʾān and Ḥadīth Based Ruling
Source: Aḥkām wa Masāʾil – Nikāḥ ke Masāʾil, Volume 1, Page 317
❓ Background of the Question:
We are two real brothers. My elder brother has five daughters, and I myself have two sons. My wife and my brother’s wife are real sisters. On one occasion, my wife breastfed one of my elder brother’s daughters. Now my question is: Can my younger son marry my brother’s younger daughter? Please provide complete guidance on this matter in the light of the Qurʾān and Ḥadīth.
✅ Answer:
Al-ḥamdu lillāh, waṣ-ṣalātu was-salāmu ʿalā Rasūlillāh, Ammā Baʿd!
Allah ﷻ says in the Qurʾān:
﴿وَأُمَّهَٰتُكُمُ ٱلَّٰتِيٓ أَرۡضَعۡنَكُمۡ وَأَخَوَٰتُكُم مِّنَ ٱلرَّضَٰعَةِ﴾
(al-Nisāʾ: 23)
“And your mothers who nursed you, and your foster sisters (are forbidden to you in marriage).”
The Prophet ﷺ said:
«اَلرَّضَاعَةُ تُحَرِّمُ مَا تُحَرِّمُ الْوِلَادَةُ»
(Ṣaḥīḥ al-Bukhārī, Kitāb al-Nikāḥ, Bāb: Wa-ummahātukum allatī arḍaʿnakum)
“Breastfeeding makes unlawful the same relations that blood relations make unlawful.”
📖 Sharʿī Explanation of the Issue:
- If your wife breastfed your brother’s daughter within two years of age, and the child nursed five times or more, then that girl becomes the foster daughter of your wife.
- Consequently, your son and that girl will become foster siblings.
❀ Therefore, marriage between your son and that girl will not be permissible.
❀ Because by the bond of Riḍāʿah, they are regarded as brother and sister.
⚖ Important Note:
- If breastfeeding took place after two years of age, or if the child nursed less than five times, then the matter would differ and would require further detailed investigation.
🔑 Conclusion:
If your wife breastfed your brother’s daughter five or more times within two years of her age, then that girl is a foster sister to your sons. In such a case, marriage between them is ḥarām (forbidden) in Sharīʿah.
ھذا ما عندي والله أعلم بالصواب
