What is forbidden in the seventh commandment?

Answer

The seventh commandment forbids all impure thoughts (; ), words (; ), and actions ().

Read the 5 proof texts (KJV)

Matthew 5:28: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.
Colossians 4:6: Let your speech [be] alway with grace, seasoned with salt, that ye may know how ye ought to answer every man.
Ephesians 5:4: Neither filthiness, nor foolish talking, nor jesting, which are not convenient: but rather giving of thanks.
2 Timothy 2:22: Flee also youthful lusts: but follow righteousness, faith, charity, peace, with them that call on the Lord out of a pure heart.
Ephesians 5:3: But fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints;