Genesis 49:5-7
Simeon and Levi are brothers; their swords are weapons of violence. / May I never enter their council; may I never join their assembly. For they kill men in their anger, and hamstring oxen on a whim. / Cursed be their anger, for it is strong, and their wrath, for it is cruel! I will disperse them in Jacob and scatter them in Israel.

Exodus 34:16
And when you take some of their daughters as brides for your sons, their daughters will prostitute themselves to their gods and cause your sons to do the same.

Deuteronomy 7:3-4
Do not intermarry with them. Do not give your daughters to their sons or take their daughters for your sons, / because they will turn your sons away from following Me to serve other gods. Then the anger of the LORD will burn against you, and He will swiftly destroy you.

Joshua 9:14-15
Then the men of Israel sampled their provisions but did not seek the counsel of the LORD. / And Joshua made a treaty of peace with them to let them live, and the leaders of the congregation swore an oath to them.

Judges 14:1-3
One day Samson went down to Timnah, where he saw a young Philistine woman. / So he returned and told his father and mother, “I have seen a daughter of the Philistines in Timnah. Now get her for me as a wife.” / But his father and mother replied, “Can’t you find a young woman among your relatives or among any of our people? Must you go to the uncircumcised Philistines to get a wife?” But Samson told his father, “Get her for me, for she is pleasing to my eyes.”

2 Samuel 13:12-14
“No, my brother!” she cried. “Do not violate me, for such a thing should never be done in Israel. Do not do this disgraceful thing! / Where could I ever take my shame? And you would be like one of the fools in Israel! Please speak to the king, for he will not withhold me from you.” / But Amnon refused to listen to her, and being stronger, he violated her and lay with her.

1 Kings 11:1-2
King Solomon, however, loved many foreign women along with the daughter of Pharaoh—women of Moab, Ammon, Edom, and Sidon, as well as Hittite women. / These women were from the nations about which the LORD had told the Israelites, “You must not intermarry with them, for surely they will turn your hearts after their gods.” Yet Solomon clung to these women in love.

Nehemiah 13:25-27
I rebuked them and called down curses on them. I beat some of these men and pulled out their hair. Then I made them take an oath before God and said, “You must not give your daughters in marriage to their sons or take their daughters as wives for your sons or for yourselves! / Did not King Solomon of Israel sin in matters like this? There was not a king like him among many nations, and he was loved by his God, who made him king over all Israel—yet foreign women drew him into sin. / Must we now hear that you too are doing all this terrible evil and acting unfaithfully against our God by marrying foreign women?”

Psalm 106:35
but they mingled with the nations and adopted their customs.

Proverbs 6:32
He who commits adultery lacks judgment; whoever does so destroys himself.

Proverbs 7:21-23
With her great persuasion she entices him; with her flattering lips she lures him. / He follows her on impulse, like an ox going to the slaughter, like a deer bounding into a trap, / until an arrow pierces his liver, like a bird darting into a snare—not knowing it will cost him his life.

Matthew 5:28
But I tell you that anyone who looks at a woman to lust after her has already committed adultery with her in his heart.

Matthew 15:19
For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, and slander.

Mark 7:21-23
For from within the hearts of men come evil thoughts, sexual immorality, theft, murder, adultery, / greed, wickedness, deceit, debauchery, envy, slander, arrogance, and foolishness. / All these evils come from within, and these are what defile a man.”

John 8:34
Jesus replied, “Truly, truly, I tell you, everyone who sins is a slave to sin.