This is because frequently in Arabic and in Quran (as in some of the verses on inheritance), the term "mother" includes the grandmother and ascending.Those Permanently Forbidden Because of Marital Relations Wives of ascendants no matter how far (father's wife, grandfather's wife, etc.).Another time, the brother of a woman who had breastfed Ai'shah came to visit her.She refused to let him in until she asked the Prophet (peace and blessings be upon him) about it and he said: "Give him permission for he is our uncle." Minimum Requirement in Breast Feeding There is a wide variety of opinion on how many "sessions" of breastfeeding create the prohibition including one, five, ten, seven and three.The ruling holds whether the step-daughter was ever under his care or not. Those Permanently Forbidden Due to Breast Feeding The verse actually mentions "mothers" and "sisters" by breast feeding.From these two, the other can be derived based on the hadith of the Prophet (peace and blessings be upon him): "Breast feeding make forbidden what is forbidden through blood relations." In another hadith, the Prophet (peace and blessings be upon him) was asked to marry the daughter of his uncle Hamza and he said: "She is not permissible for me.Descendants of wives (step-daughters and their children) only if the man consummated the marriage with the wife in question.
Allah mentioned most of the categories of women involved in this question in the following verses: "And do not marry women whom your fathers married except what has already passed. (22) Forbidden to you in marriage are: your mothers, your daughters, your sisters, your father's sisters, your mother's sisters, your brother's sisters, your sister's daughters, your wet nurse, your 'sisters' by nursing, your wives mothers, your step daughters under your guardianship born of your wives with whom you have consummated - if you did not consummate then there is no sin upon you, the wives of your blood sons, two sisters at the same time, except for that which has already passed. (23) And those already married except those whom your right hand possesses (through capture). And allowed for you are all besides these if you seek them with your property seeking chastity not fornication..." Those Who Are Forbidden Forever This category includes those one is forbidden to marry due to relationship of blood as well as some who are forbidden due to marital relations.
Those Forbidden Due to Blood Relations Descendants due to a relationship with a woman no matter how far (a man's daughter, granddaughter, etc.) Ascendants of women no matter how far (mother, maternal and paternal grandmother, etc.) Descendants from his parents no matter how far (sisters, half sisters, sisters children, etc.) Siblings of male and female ascendants no matter how far (paternal and maternal aunts, great aunts, etc.) The student may notice that of these, the grandmother was not explicitly mentioned in the verse.