What is the wisdom behind spending on relatives?

Providing for needy relatives is obligatory upon the affluent because it is an act of maintaining kinship ties, showing compassion, and fulfilling the rights of kinship. Disbelief does not negate these rights. Allah Almighty enjoined kindness to relatives in Surah An-Nisa', and the highest form of kindness is to provide for them in times of necessity and need. Allah has forbidden the severing of kinship ties, and leaving a disbelieving relative to die of hunger and thirst, when one has the ability to relieve their distress, is considered the gravest form of severing kinship ties.