What is the ruling on using an expensive perfume containing musk in prayer, given ignorance of the musk's source, and does it matter whether the musk is extracted from a dead animal like a deer, or from a live or dead animal, or from the secretions of the civet cat, concerning its purity and the permissibility of using it in prayer?

It is permissible for you to pray in a garment that has perfume on it, the source of which you are unaware, for the basic principle regarding things is purity. Musk is pure if it is extracted from a living animal or one that has been ritually slaughtered. However, if it is extracted from a dead animal that has not been ritually slaughtered, it is impure. Civet is considered pure by some scholars. It is either the milk of a sea cat or the sweat of a wild cat, but it may be mixed with animal hair.