Ruling on Marriage Between Children of Sisters in Light of Fosterage (Riḍāʿah)
📚 Source: Fatāwā Muḥammadiyyah, Vol. 1, Pg. 739
❖ Question:
Hindah and Fareedah are two real sisters. Hindah has a son who is being breastfed, and Fareedah has a daughter who is also breastfeeding. One day, while Hindah is out for errands, Fareedah breastfeeds Hindah’s son.
This act causes Hindah’s son and Fareedah’s daughter to become milk-siblings (raḍāʿī brother and sister).
Later, Fareedah’s daughter (the foster sister) passes away. Subsequently, Fareedah gives birth to another daughter.
The question is:
Can Hindah’s son (who was breastfed by Fareedah) marry this second daughter of Fareedah?
Please issue a verdict based on the Qur’an and Sunnah.
❖ Answer:
Al-ḥamdu lillāh, waṣ-ṣalātu was-salāmu ʿalā Rasūlillāh. Ammā baʿd:
In the given situation, it is clear that Fareedah breastfed Hindah’s son, making her his foster mother (raḍāʿī mother).
As a result, all daughters of Fareedah become his foster sisters (raḍāʿī sisters), regardless of whether they were breastfed or not, or whether they were born before or after the fosterage occurred.
❖ Qur’anic Evidence:
﴿وَأَخَوَاتُكُم مِّنَ الرَّضَاعَةِ﴾
“…and your milk-sisters are also forbidden to you (for marriage).”
📖 (Surah al-Nisāʾ: 23)
This verse makes it clear that foster sisters are just as unlawful for marriage as biological sisters.
❖ Hadith Evidence:
“يَحْرُمُ مِنَ الرَّضَاعَةِ مَا يَحْرُمُ مِنَ النَّسَبِ“
“Whatever is prohibited through lineage is also prohibited through breastfeeding.”
📚 (Authentic Hadith in various collections)
Thus, all the relationships that are unlawful by blood become unlawful through valid riḍāʿah (fosterage) as well.
✅ Ruling:
☑ Since Fareedah breastfed Hindah’s son, she became his foster mother.
☑ Therefore, all of Fareedah’s daughters — past, present, or future — are his milk-sisters.
☑ As such, Hindah’s son cannot marry any of Fareedah’s daughters, even if they never nursed from the same woman themselves.
❖ Exception:
If Hindah has other sons who were never breastfed by Fareedah, then:
✔ They may marry Fareedah’s daughters,
✔ Because no biological or foster relationship exists between them that would prohibit such a marriage.
✅ Final Summary:
➊ Fareedah is the foster mother of Hindah’s son.
➋ All of Fareedah’s daughters are his foster sisters.
➌ He may not marry any of them.
➍ Other sons of Hindah (not breastfed by Fareedah) may marry Fareedah’s daughters.
وَاللهُ أَعْلَمُ بِالصَّوَابِ
