What is the wisdom behind making a vow (nadhr), and what is its ruling? Thank you very much.

The ruling and definition of vows have been previously explained. The reason for a vow is the vower's illusion that what the vow is conditioned upon will occur. This is an illusion that the Sharia has invalidated, for a vow does not change destiny. However, it aligns with destiny and extracts from the miser what he would not have otherwise wanted to give. The Sharia did not praise the act of vowing itself, but rather praised those who fulfill their vows for performing what they obligated upon themselves.