Charles Ellicott Commentary Exodus 28:42

"And thou shalt make them linen breeches to cover the flesh of their nakedness; from the loins even unto the thighs they shall reach:" — Exodus 28:42 (ASV)

You shall make them linen breeches. —Rather, linen drawers. Drawers reaching from the waist to a little above the knee were the sole garment of many in Egypt, a necessary garment of all. Their object was as here stated.