Woe to thee, Moab! thou art undone, O people of {m} Chemosh: he hath given his sons that escaped, and his daughters, into captivity unto Sihon king of the Amorites.

(m) Chemosh was the idol of the Moabites, 1Ki 11:33 who was not able to defend his worshippers, who took the idol for their father.

Wesley's Notes

21:29 People of Chemosh - The worshippers of Chemosh: so the God of the Moabites was called. He, that is, their God, hath delivered up his own people to his and their enemies; nor could he secure even those that had escaped the sword, but suffered them to be carried into captivity. The words of this and the following verse seem to be not a part of that triumphant song made, by some Amoritish poet, which seems to be concluded, Nu 21:28, but of the Israelites making their observation upon it. And here they scoff at the impotency not only of the Moabites, but of their God also, who could not save his people from the sword of Sihon and the Amorites.

Jamieson-Fausset-Brown Bible Commentary

29. people of Chemosh-the name of the Moabite idol (1Ki 11:7-33; 2Ki 23:13; Jer 48:46).

he-that is, their god, hath surrendered his worshippers to the victorious arms of Sihon.

Matthew Henry's Concise Commentary

21:21-35 Sihon went with his forces against Israel, out of his own borders, without provocation, and so ran upon his own ruin. The enemies of God's church often perish by the counsels they think most wisely taken. Og, king of Bashan, instead of being warned by the fate of his neighbours, to make peace with Israel, makes war with them, which proves in like manner his destruction. Wicked men do their utmost to secure themselves and their possessions against the judgments of God; but all in vain, when the day comes on which they must fall. God gave Israel success, while Moses was with them, that he might see the beginning of the glorious work, though he must not live to see it finished. This was, in comparison, but as the day of small things, yet it was an earnest of great things. We must prepare for fresh conflicts and enemies. We must make no peace or truce with the powers of darkness, nor even treat with them; nor should we expect any pause in our contest. But, trusting in God, and obeying his commands, we shall be more than conquerors over every enemy.