Joshua 22:17

Do you remember our sin at Peor, when Jehovah punished his own people with an epidemic? We are still suffering because of that. Was that not enough sin?

Numbers 25:1-18

While Israel remained at Shittim, the people indulged in sexual immorality with the Moabite women.

Deuteronomy 4:3-4

You saw how he killed everyone who worshiped the god Baal at Peor.

Psalm 106:28-29

They joined in worshiping the god Baal while they were at Peor. They ate what was sacrificed to the dead.

Ezra 9:13-14

After all this and because of our evil-doing and our great sin, and seeing that the punishment that you, O God, have given us, is less than the measure of our sins, and that you have kept from death those of us who are here;

1 Corinthians 10:8

Do not commit fornication like some of them committed. Twenty three thousand of them died in one day.

1 Corinthians 10:11

These things happened for examples, and they are written for our instruction, upon whom the end of the ages has come.

Treasury of Scripture Knowledge

Summary

Is the iniquity of Peor too little for us, from which we are not cleansed until this day, although there was a plague in the congregation of the LORD,

Bible References

Is the iniquity

Numbers 25:3
So Israel joined itself to Baal of Peor. Jehovah was angry against Israel.
Deuteronomy 4:3
You saw how he killed everyone who worshiped the god Baal at Peor.
Psalm 106:28
They joined in worshiping the god Baal while they were at Peor. They ate what was sacrificed to the dead.

From which

Ezra 9:13
After all this and because of our evil-doing and our great sin, and seeing that the punishment that you, O God, have given us, is less than the measure of our sins, and that you have kept from death those of us who are here;
1 Corinthians 10:8
Do not commit fornication like some of them committed. Twenty three thousand of them died in one day.