25:3 Baal-peor. This was the introduction of Baal worship into Israel, a practice which plagued them off and on until the Babylonians carried them into exile over a thousand years later. Baal-peor was evidently the shrine to Baal on the mountain of Peor (Numbers 23:28). When Balaam was not allowed by God to curse Israel directly, he counseled Balak to infiltrate the armies of Israel through using the Moabite women to seduce them. This action resulted in immediate capital punishment for all who became involved in this way. Balaam himself was later slain because of this counsel (Numbers 31:8,16).

25:4 heads of the people. The “heads of the people” were their leaders (compare Numbers 7:2) whom God held responsible for the sudden apostasy. The priests of Baal had inveigled many of the people to participate in a pagan feast to their fake god, one of the temptations being the prostitution which was part of the “worship.” Both the idolatry and the fornication were contrary to God’s law, and were the very sins which God had commissioned His people to exterminate from the promised land. It was essential, especially at this crucial juncture of their mission of conquest, that these gross and presumptuous sins be severely punished, before the corruption could spread further.

25:9 twenty and four thousand. According to I Corinthians 10:8, 23,000 fell “in one day.” Evidently another thousand died a day or so later.