Numbers 25:6

Then Aaron took it as Moses had spoken, and ran into the midst of the assembly, for behold, the plague had begun among the people. So he put on the incense and made atonement for the people.

“Behold, these caused the sons of Israel, through the word of Balaam, to act unfaithfully against Yahweh in the matter of Peor, so the plague was among the congregation of Yahweh.

“Your eyes have seen what Yahweh has done in the case of Baal-peor, for all the men who walked after Baal-peor, Yahweh your God has destroyed them from among you.

‘Is the iniquity of Peor too small a thing for us, from which we have not cleansed ourselves to this day, although there was a plague on the congregation of Yahweh?

Nor let us act in sexual immorality, as some of them did, and twenty-three thousand fell in one day.