1 Thessalonians 4:3, 6
1 Thessalonians 4:3 ESV
For this is the will of God, your sanctification: that you abstain from sexual immorality
1 Thessalonians 4:6 ESV
that no one transgress and wrong his brother in this matter, because the Lord is an avenger in all these things, as we told you beforehand and solemnly warned you.