Revelation 2:14-15

"Nevertheless, I have a few things against you: You have people there who hold to the teaching of Balaam, who taught Balak to entice the Israelites to sin by eating food sacrificed to idols and by committing sexual immorality. Likewise you also have those who hold to the teaching of the Nicolaitans."

Nevertheless, I have a few things against you
Revelation 2:20 "Nevertheless, I have this against you: You tolerate that woman Jezebel, who calls herself a prophetess. By her teaching she misleads my servants into sexual immorality and the eating of food sacrificed to idols." (Thyatira)

You have people there who hold to the teaching of Balaam
2 Peter 2:15 They have left the straight way and wandered off to follow the way of Balaam son of Beor, who loved the wages of wickedness.
Numbers 25:1-2 While Israel was staying in Shittim, (after Balaam's oracles) the men began to indulge in sexual immorality with Moabite women, who invited them to the sacrifices to their gods. The people ate and bowed down to their gods.
Jude 11 Woe to them! They have taken the way of Cain; they have rushed for profit into Balaam's error; they have been destroyed in Korah's rebellion.

who taught Balak to entice the Israelites to sin by eating food sacrificed to idols
Numbers 31:16 "They (the Moabite women) were the ones who followed Balaam's advice and were the means of turning the Israelites away from the LORD in what happened at Peor, so a plague struck the LORD's people."
Acts 15:20 Instead we should write to them, telling them to abstain from food polluted by idols, from sexual immorality, from the meat of strangled animals and from blood.
Acts 15:29 You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things. Farewell.

and by committing sexual immorality
1 Corinthians 6:13 "Food for the stomach and the stomach for food"--but God will destroy them both. The body is not meant for sexual immorality, but for the Lord, and the Lord for the body.

You also have those who hold to the teaching of the Nicolaitans
Revelation 2:6 "But you have this in your favor: You hate the practices of the Nicolaitans, which I also hate." (Ephesus)

(parentheses are mine)

Scriptures taken from the Holy Bible, New International Version® NIV®, Copyright© 1973, 1978, 1984 by International Bible Society. Used by permission. All rights reserved worldwide.