Moses
Numbers 22:4BSB·traditional attribution

So the Moabites said to the elders of Midian, “This horde will devour everything around us, as an ox licks up the grass of the field.” Since Balak son of Zippor was king of Moab at that time,

Matthew Henry Presbyterian @wholebiblehenry

The children of Israel have at length finished their wanderings in the wilderness, out of which they went up (Num 21:18), and are now encamped in the plains of Moab near Jordan, where they continued till they passed through Jordan under Joshua, after the death of Moses. Now we have here, I. The fright which the Moabites were in upon the approach of Israel, Num 22:2-4.

Commenting on Numbers 22:1-14

John Gill Reformed Baptist @doctorgill

He sent messengers therefore unto Balaam the son of Beor,.... In consequence of the consultation held by the king of Moab with the elders of Midian; and very probably through a motion of theirs, and by advice they gave, Balak dispatched messengers of both people to the person here described by his name and parentage; but who he was is not easy to say: the...

Jamieson-Fausset-Brown Reformed @jfbcommentary

elders of Midian--called kings (Num 31:8) and princes (Jos 13:21). The Midianites, a distinct people on the southern frontier of Moab, united with them as confederates against Israel, their common enemy.