Q: My inquiry is about the wedding of my brother-in-law who is a Magus.Should we travel with him to conclude his marriage contract with his fiancée? Should we help him with money for example, knowing that my husband is the only Muslim in his family, while I am Muslim by birth?
What are the legal rulings that regulate dealing with non-Muslim people,
like the members of my husband's family?
It is not permissible for a Muslim to have Wala' (loyalty) to unbelievers, represented in this particular situation by attending the celebration of your brother-in-law's marriage and traveling with him for this purpose. The wedding celebrations and the like include some rites associated with Kufr (disbelief).May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.