Leviticus 20:10
"And the man that committeth adultery with another man’s wife, even he that committeth adultery with his neighbour’s wife, the adulterer and the adulteress shall surely be put to death."
Cross References (ranked by relevance)
Deuteronomy 5:18
Neither shalt thou commit adultery.
Leviticus 18:20
Moreover thou shalt not lie carnally with thy neighbour’s wife, to defile thyself with her.
Exodus 20:14
Thou shalt not commit adultery.
2 Samuel 12:13
And David said unto Nathan, I have sinned against the LORD. And Nathan said unto David, The LORD also hath put away thy sin; thou shalt not die.