Is it permissible to marry the daughter of one's maternal uncle if the paternal grandmother—the mother's mother—nursed the questioner, knowing that the maternal uncle was not nursed by the grandmother simultaneously with the questioner, and neither was the maternal uncle's daughter?

"What is prohibited by lineage is also prohibited by breastfeeding," as the Prophet, peace and blessings be upon him, said: "What is prohibited by lineage is prohibited by breastfeeding." So, if a person is breastfed by a woman five full feedings within the first two years of life, he becomes her son and the son of her husband, the owner of the milk, and a brother to her children through breastfeeding. If you were breastfed by your grandmother, your maternal uncle's mother, five full feedings within the first two years, you have become her son and your maternal uncle's brother through breastfeeding. Therefore, it is not permissible for you to marry his daughter because she is your niece through breastfeeding. However, if the breastfeeding was less than five feedings or occurred after the first two years, the prohibition does not apply, and it is permissible for you to marry your maternal uncle's daughter, unless there is another cause for prohibition between you.