Exodus 20:14 You shall not commit adultery.

Leviticus 18:20

Do not have sexual relations with your neighbor's wife and defile yourself with her.

Proverbs 5:3-9  For the lips of an adulteress drip honey, and her speech is smoother than oil; but in the end she is bitter as gall, sharp as a double-edged sword. Her feet go down to death; her steps lead straight to the grave. She gives no thought to the way of life; her paths are crooked, but she knows it not.

Proverbs 5:19-20  Why be captivated, my son, by an adulteress? Why embrace the bosom of another man's wife? For a man's ways are in full view of the LORD, and he examines all his paths. The evil deeds of a wicked man ensnare him; the cords of his sin hold him fast.

Proverbs 5:27-29 Can a man scoop fire into his lap without his clothes being burned? Can a man walk on hot coals without his feet being scorched? So is he who sleeps with another man's wife; no one who touches her will go unpunished.

Proverbs 5:32  But a man who commits adultery lacks judgment; whoever does so destroys
himself.

Matthew 5:27, 28, 32 You have heard that it was said, 'Do not commit adultery.' But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart. But I tell you that anyone who divorces his wife, except for marital unfaithfulness, causes her to become an adulteress, and anyone who marries the divorced woman commits adultery.

John 8:4-11 [They] said to Jesus, "Teacher, this woman was caught in the act of

adultery. In the Law Moses commanded us to stone such women. Now what do you say?" They were using this question as a trap, in order to have a basis for accusing him. But Jesus bent down and started to write on the ground with his finger. When they kept on questioning him, he straightened up and said to them, "If any one of you is without sin, let him be the first to throw a stone at her." Again he stooped down and wrote on the ground. At this, those who heard began to go away one at a time, the older ones first, until only Jesus was left, with the woman still standing there. Jesus straightened up and asked her, "Woman, where are they? Has no one condemned you?" "No one, sir," she said. "Then neither do I condemn you," Jesus
declared. "Go now and leave your life of sin."

Hebrews 13:4 Marriage should be honored by all, and the marriage bed kept
pure, for God will judge the adulterer and all the sexually immoral.