breastfeeding that affects marriageability refers to breast-feeding a baby for at least five times during the first two years of the baby's life. If your cousin had sucked your mother's milk for this number of times, she would be your mother's daughter by breastfeeding and your sister by breastfeeding, even if she drank this breast milk from a bottle. Subsequently, it is not permissible for you to marry her, because she is your sister by breastfeeding. (Part No. 21; Page No. 13) Allah (Exalted be He) says:
Forbidden to you (for marriage) are: your mothers, your daughters
to His Saying:
...your foster milk suckling sisters
Allah (Exalted be He) also says:
The mothers shall give suck to their children for two whole years
It was authentically reported that the Prophet (peace be upon him) said:
"Breastfeeding makes unlawful what parturition makes unlawful (regarding marital affairs)."
It was authentically reported on the authority of
`Aishah (may Allah be pleased with her) who narrated: "It was revealed in the Qur'an: "Ten exact times of breastfeeding affect marriageability.' Then this was abrogated by: 'Five exact times' and the Prophet (peace be upon him) then died while the ruling was settled as such."It should be noted that one breastfeeding counts when the baby holds the breast and sucks milk from it. If the baby releases the breast then holds it and sucks milk again, this is a second time of breastfeeding and so on.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.