The breastfeeding that affects marriageability refers to breast-feeding a baby for five times or more during the first two years of the baby's life. One breastfeeding is counted when the baby holds the breast and sucks milk from it into the stomach. If the baby releases the breast then holds it and sucks milk again, this is a second breastfeeding and so on. (Part No. 21; Page No. 110) If both the woman and you were breast-fed five times or more by your maternal grandmother during your first two years of life, and if the girl you want to marry was breast-fed five times or more during the first two years of her life by the woman who was also breast-fed by your maternal grandmother, it would be prohibited for you to marry that girl since she would be considered your niece by breastfeeding. Allah (Exalted be He) says:
Forbidden to you (for marriage) are: your mothers
Allah also says:
The mothers shall give suck to their children for two whole years, (that is) for those (parents) who desire to complete the term of suckling
The Prophet (peace be upon him) also said:
"Breastfeeding relationships are equal to blood relationships in rendering (marriage) unlawful."
(Agreed upon by Al-Bukhari and Muslim)
It was authentically reported on the authority of
`Aishah (may Allah be pleased with her) that she said, "It had been revealed in the Qur'an that ten clear times of breastfeeding affect marriageability, then it was abrogated (and substituted) by five clear times (of breastfeeding). Allah's Messenger (peace be upon him) died and the matter was settled as such." If the times of breastfeeding were less than five or if breastfeeding did not take place during the first two years of life, you would be permitted to marry her. (Part No. 21; Page No. 111) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.