Moses
Leviticus 21:3BSB·traditional attribution

or his unmarried sister who is near to him, since she has no husband.

Matthew Henry Presbyterian @wholebiblehenry

It was before appointed that the priests should teach the people the statutes God had given concerning the difference between clean and unclean, Lev 10:10, Lev 10:11. Now here it is provided that they should themselves observe what they were to teach the people. Note, Those whose office it is to instruct must do it by example as well as precept, Ti1 4:12.

Commenting on Leviticus 21:1-9

John Gill Reformed Baptist @doctorgill

And for his sister a virgin, that is nigh unto him,.... That is, his sister by both father's and mother's side, as Aben Ezra; though, according to Gersom, his sister by his father's side, and not by his mother's side, is meant; but, according to Alphes, by his mother's side: perhaps this may signify not nearness of kin, which is expressed by being his sister...

Geneva Bible Notes Reformed @genevanotes

And for his sister a virgin, that is nigh unto him, which hath had no husband; for her may he be defiled. (b) For being married she seemed to be cut off from his family.