(Mufti. Shah Rafi Uddin Hamdani & Dr. Imran Khan)
Foster brothers and sisters are those relatives who are related because they suckled from the same woman. ProphetMuhammad
was suckled by various women, therefore he had numerous foster brothers and sisters. Their details are given below:
Through Thuwaybah 
. He was a paternal uncle of the Holy Prophet
but since they had suckled from the same woman, he was his foster brother as well.
who was the son of Prophet Muhammad’s
paternal aunt. Hence, he was his cousin and foster brother.
was Thuwaybah’s
own son who became a foster brother to Prophet Muhammad
. 1
. He was his cousin and his foster brother.
was a paternal cousin and a foster brother of the Holy Prophet
. 2 Through Halimah Sadiya 
was Halimah Sadiya’s
own son who became Prophet Muhammad's
foster brother.
were daughters of Halimah Sadiya
who became Prophet Muhammad's
foster sisters.
ibn Harith ibn Abdul Muttalib who was a distant paternal cousin of the Holy Prophet
, became his foster brother as well. 3Islam gave these nursing mothers and relations a special status in the family. If a child is reared and breastfed by a woman other than the real mother, she is called Umm-e-Rada'ah (ام رضاعۃ) (foster mother, or milk mother). Her children are treated as real brothers and sisters and marrying with them is prohibited. Thus, a woman who nurses a child, becomes mother by milk-relation. Her suckled child is considered as a full sibling to the foster-mother’s other children, and as mahram to the woman. Islam stands unique to accord such a status to the suckling mothers.