Q: Why do muslims not remove any hair, not cut nails or trim mustaches in the first ten days of hajj? Nonmuslim, just curious.
A: The cutting of these hairs, nails, etc. should be done prior to the first ten days. Not removing them is mustahab (higly preferred action.) It is not fard (compulsory to do so). This behavior is to resemble the hujjaj (those in hajj.)
We appreciate your query.
Allah Certainly Knows Best.