Charles H. Spurgeon on Psalms 106:29

Thus they provoked him to anger with their inventions: and the plague brake in upon them. Open licentiousness and avowed idolatry were too gross to be winked at. This time the offences clamoured for judgment, and the judgment came at once. Twenty-four thousand persons fell before a sudden and deadly disease which threatened to run through the whole camp. Their new sins brought on them a disease new to their tribes. When men invent sins God will not be slow to invent punishments. Their vices were a moral pest, and they were visited with a bodily pest: so the Lord meets like with its like.