A Question Regarding Breast-feeding

Question :

I want to marry the daughter of my maternal uncle. But there is a person who was breast-fed with my uncle by my grandmother, so he has become my maternal uncle through breast-feeding. This daughter of my maternal uncle was breast-fed by the mother of this person, so she has become his sister through breast-feeding. Is it permissible for me to marry my maternal uncle's daughter, bearing in mind that there is no breast-feeding between us neither from my mother, nor from her mother?

Answer:

Before answering this question, I would like to make clear that the breast-feeding which prohibits (marriage) is that which takes place on five clear occasions or more, during the first two years before weaning, anything less than five times has no effect. So if a child was breast-fed by a woman four times, he would not be a son to her, because there must be five breast- feedings. This is confirmed in Sahih Muslim from the Hadith of 'A'ishah, may Allah be pleased with her.

When this is clear, then (it is obvious that) this man who was breast-fed by your grandmother is not an uncle to you, unless the conditions of breast-feeding were fulfilled. If he were an uncle, then the daughter of your uncle whom you wish to marry would be permissible for you, even if she was breast-fed by the mother of this man who was breast-fed with your uncle by your grandmother. This is because prohibition is not transmitted by breast-feeding except to the one who is breast-fed and his descendants. As for the relatives of the one who was breast-fed, such as Al-Usul (parents, grandparents etc.) and Al-Hawashi (uncles, cousins etc.), the breast-feeding is not transmitted to them.

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 6 Pages 119-120