In the first place, we must make it clear that in Islam it is not permitted to adopt a child and name him after his adoptive parents, while denying his biological parents. The Qur’an refers to this saying: “Proclaim their real parentage. That will be more equitable in the sight of Allah. And if ye know not their fathers, then (they are) your brethren in the faith, and your clients.” (Al-Ahzab: 4)
However, Islam does allow Muslims to raise children who are not theirs. Muslims can fully raise these children, look after them, and support them, but they must name the children after their real fathers. They can also bequeath to them up to one third of their estate, but such foster children do not inherit from the foster parents.
Dr. Muzammil H. Siddiqi, former President of the Islamic Society of North America states: “Adoption (tabanni) in the sense of changing the name of a child’s biological parents is not permissible in Islam. However, if one takes care of a child as a custodian or guardian and wants to write something for that child in his/her will, then one is allowed to do that within one third of his/her estate. One is allowed to give up to one third of one’s wealth to any charity or to anyone who would not receive any share of the inheritance otherwise.”