Can a non-Muslim have custody over a Muslim child?
Chapter on Who is More Entitled to Child Custody
Al-Mughni
Book of Maintenance (Nafaqāt)
Primary text
Custody is not established for a non-Muslim over a Muslim child. This is the position of Malik, Ash-Shafi'i, Suwar, and Al-'Anbari. The primary reasoning is that custody is a form of legal authority (*wilayah*), and such authority is not granted to a non-Muslim over a Muslim, similar to the authority in marriage or property. Furthermore, if custody is denied to a transgressor, it is more rightly denied to the disbeliever, whose potential harm is greater by corrupting the child's religion through teaching them disbelief. Since custody must serve the child's best interest, it should not be established in a manner that leads to the destruction of the child or their faith.
Supporting text
Ibn al-Qasim, Abu Thawr, and the People of Opinion permit it based on the narration concerning Rafi' ibn Sinan, whose non-Muslim wife refused to embrace Islam, and the Prophet (peace be upon him) ultimately awarded the child to the father after the child inclined toward the mother, then the father upon prayer. Another justification suggests the Prophet's judgment was specific to that instance. Ibn al-Mundhir noted that the chain of transmission for the narration is weak.