Moses
Leviticus 23:20ESV·traditional attribution

And the priest shall wave them with the bread of the firstfruits as a wave offering before the LORD, with the two lambs. They shall be holy to the LORD for the priest.

Matthew Henry Presbyterian @wholebiblehenry

Here is the institution of the feast of pentecost, or weeks, as it is called (Deu 16:9), because it was observed fifty days, or seven weeks, after the passover. It is also called the feast of harvest, Exo 23:16. For as the presenting of the sheaf of first-fruits was an introduction to the harvest, and gave them liberty to put in the sickle, so they...

Commenting on Leviticus 23:15-22

John Gill Reformed Baptist @doctorgill

And the priests shall wave them with the bread of the firstfruits,.... The two loaves called the two wave loaves, Lev 23:17; with which were waved the two lambs of the peace offerings; and these alive, as Jarchi and Ben Gersom intimate.

Jamieson-Fausset-Brown Reformed @jfbcommentary

FEAST OF PENTECOST. (Lev 23:15-22) ye shall count unto you from the morrow after the sabbath--that is, after the first day of the passover week, which was observed as a Sabbath.

Commenting on Leviticus 23:15-22