Exodus 28 · a question people ask
Why does God care so much about what the priests wear?
The chapter gives its own reasons. The garments are "for glory and for beauty" (28:2), made "to sanctify him, that he may minister to me in the priest’s office" (28:3). The bells are heard "when he goes in to the holy place before the LORD, and when he comes out, that he not die" (28:35). The gold plate is on his forehead "that they may be accepted before the LORD" (28:38). The linen pants are "to cover their naked flesh" (28:42), as the altar was to have no steps, "that your nakedness may not be exposed to it" (20:26). Most of the reasons have to do with going in before the LORD.
The verses
“You shall make holy garments for Aaron your brother, for glory and for beauty. You shall speak to all who are wise-hearted, whom I have filled with the spirit of wisdom, that they make Aaron’s garments to sanctify him, that he may minister to me in the priest’s office.”
“It shall be on Aaron to minister: and its sound shall be heard when he goes in to the holy place before the LORD, and when he comes out, that he not die.”
“It shall be on Aaron’s forehead, and Aaron shall bear the iniquity of the holy things, which the children of Israel shall make holy in all their holy gifts; and it shall be always on his forehead, that they may be accepted before the LORD.”
“You shall make them linen pants to cover their naked flesh. They shall reach from the waist even to the thighs. They shall be on Aaron and on his sons, when they go in to the Tent of Meeting, or when they come near to the altar to minister in the holy place, that they don’t bear iniquity, and die. This shall be a statute forever to him and to his offspring after him.”