Source: Fatāwā Muḥammadiyyah, Volume 1, Page 741
Zayd has two wives. From one wife, a daughter was born who was breastfed by her mother. Bakr, a relative of Zayd, was breastfed by Zayd’s other wife. The question is:
Is it permissible for Bakr to marry Zayd’s daughter?
الحمد لله، والصلاة والسلام علىٰ رسول الله، أما بعد!
According to the scenario presented, Bakr becomes the foster son (رضاعی بیٹا) of Zayd because he drank the milk of Zayd’s second wife. In matters of fosterage, both husband and wife are jointly considered as foster parents, since the milk is attributed to the husband’s seed (due to pregnancy through him).
Therefore, Bakr and the daughter of Zayd’s second wife are foster siblings (رضاعی بہن بھائی).
Just as marriage between biological siblings is prohibited, similarly, marriage between foster siblings is also categorically forbidden in Islamic law.
عن علي رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم:
"إن الله حرم من الرضاع ما حرم من النسب"
“Indeed, Allah has prohibited (marriage due to) suckling what He has prohibited due to blood relations.”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 197)
وعن عائشة أن النبي صلى الله عليه وسلم قال:
"يَحرُم من الرَّضَاعَة ما يَحرُم من الولَادَة"
“Foster relationships prohibit marriage just like birth relationships do.”
This ḥadīth is ḥasan ṣaḥīḥ (authentic and sound).
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 198)
There is no disagreement among the Companions (Ṣaḥābah) and Successors (Tābiʿīn) regarding this ruling.
عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا:
“My foster uncle (Aflaḥ) came to seek permission to enter. I refused until I could ask the Messenger of Allah ﷺ. When he arrived, I asked him, and he said:
‘He is your uncle, allow him to enter.’
I said: ‘O Messenger of Allah! The woman breastfed me, not the man.’
The Prophet ﷺ replied:
**‘He is your uncle, let him in.’”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 198 – ḥadīth graded ḥasan ṣaḥīḥ)
This shows that the husband of the woman whose milk was given also becomes a foster father, and thus his relatives become maḥram (non-marriageable kin) through fosterage.
Ibn ʿAbbās رضي الله عنه was asked about a man who had two slave women.
One of them gave birth to a boy, and the other breastfed a girl.
Can the boy marry the girl?
Ibn ʿAbbās replied:
“No — the seed (i.e., source of milk) is one.”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 98)
This means the biological link of the father (Zayd) makes both children foster siblings, even if they drank from different wives of the same man.
Based on the above clear evidences from the Sunnah and statements of the Companions:
✿ Bakr is the foster son of Zayd.
✿ Zayd’s daughter (from the other wife) is Bakr’s foster sister.
✿ Therefore, marriage between them is Islamically forbidden and invalid.
هَذَا مَا عِندِي وَاللَّهُ أَعْلَمُ بِالصَّوَابِ
This is what I hold to be correct, and Allah knows best.
❖ Question:
Zayd has two wives. From one wife, a daughter was born who was breastfed by her mother. Bakr, a relative of Zayd, was breastfed by Zayd’s other wife. The question is:
Is it permissible for Bakr to marry Zayd’s daughter?
❖ Answer:
الحمد لله، والصلاة والسلام علىٰ رسول الله، أما بعد!
According to the scenario presented, Bakr becomes the foster son (رضاعی بیٹا) of Zayd because he drank the milk of Zayd’s second wife. In matters of fosterage, both husband and wife are jointly considered as foster parents, since the milk is attributed to the husband’s seed (due to pregnancy through him).
Therefore, Bakr and the daughter of Zayd’s second wife are foster siblings (رضاعی بہن بھائی).
Just as marriage between biological siblings is prohibited, similarly, marriage between foster siblings is also categorically forbidden in Islamic law.
❖ Evidences from Prophetic Traditions (Aḥādīth):
➊ Ḥadīth of ʿAlī رضي الله عنه
عن علي رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم:
"إن الله حرم من الرضاع ما حرم من النسب"
“Indeed, Allah has prohibited (marriage due to) suckling what He has prohibited due to blood relations.”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 197)
➋ Ḥadīth of ʿĀ’ishah رضي الله عنها
وعن عائشة أن النبي صلى الله عليه وسلم قال:
"يَحرُم من الرَّضَاعَة ما يَحرُم من الولَادَة"
“Foster relationships prohibit marriage just like birth relationships do.”
This ḥadīth is ḥasan ṣaḥīḥ (authentic and sound).
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 198)
There is no disagreement among the Companions (Ṣaḥābah) and Successors (Tābiʿīn) regarding this ruling.
➌ Incident of ʿĀ’ishah رضي الله عنها:
عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا:
“My foster uncle (Aflaḥ) came to seek permission to enter. I refused until I could ask the Messenger of Allah ﷺ. When he arrived, I asked him, and he said:
‘He is your uncle, allow him to enter.’
I said: ‘O Messenger of Allah! The woman breastfed me, not the man.’
The Prophet ﷺ replied:
**‘He is your uncle, let him in.’”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 198 – ḥadīth graded ḥasan ṣaḥīḥ)
This shows that the husband of the woman whose milk was given also becomes a foster father, and thus his relatives become maḥram (non-marriageable kin) through fosterage.
➍ Fatwā of Ibn ʿAbbās رضي الله عنهما:
Ibn ʿAbbās رضي الله عنه was asked about a man who had two slave women.
One of them gave birth to a boy, and the other breastfed a girl.
Can the boy marry the girl?
Ibn ʿAbbās replied:
“No — the seed (i.e., source of milk) is one.”
(Tuḥfat al-Aḥwadhī, Vol. 2, p. 98)
This means the biological link of the father (Zayd) makes both children foster siblings, even if they drank from different wives of the same man.
Conclusion:
Based on the above clear evidences from the Sunnah and statements of the Companions:
✿ Bakr is the foster son of Zayd.
✿ Zayd’s daughter (from the other wife) is Bakr’s foster sister.
✿ Therefore, marriage between them is Islamically forbidden and invalid.
هَذَا مَا عِندِي وَاللَّهُ أَعْلَمُ بِالصَّوَابِ
This is what I hold to be correct, and Allah knows best.
