Forbidden to you (for marriage) are: your mothers

A: the breastfeeding that makes a child a Mahram (unmarriageable relative) is five or more breastfeeding within the first two years of a baby’s life. If the breastfeeding of these brothers occurred in this manner, they are milk-brothers. The children of each are the milk-nieces and-nephews of the other, whether the breastfeeding relationship stems from the side of both the mother and the father, or just from the side of either the mother or the father. It is, therefore, not Halal for either of them to marry from the daughters’ of the other, because they are his milk-nieces. (Part No. 21; Page No. 117) Allah (Exalted be He) says: Forbidden to you (for marriage) are: your mothers, your daughters to His Saying: ...your foster milk suckling sisters He (Exalted be He) also says: The mothers shall give suck to their children for two whole years It is authentically reported that the Prophet (peace be upon him) said, “Breastfeeding prohibits what birth (consanguinity) prohibits.” It is also authentically reported that `Aishah (may Allah be pleased with her) said, (may Allah be pleased with her) said, "Amongst what was revealed from the Qur’an was: 'Ten known breastfeeding make (marriage) Haram (prohibited)...' It was then abrogated by: 'Five known breastfeeding...' When the Messenger of Allah (peace be upon him) died, it remained as such." It should be borne in mind that if a baby takes to a breast and sucks milk from it, and then leaves it, this is considered as one breastfeeding and if it does it again and sucks milk, this will be considered as the second breastfeeding, and so on. If the breastfeeding occurs less than five times or after the first two years of life, the child is not a Mahram and marriage is permissible.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.