Q: What is required in the seventh commandment?
A: The seventh commandment requireth the preservation of our own, and our neighbour's chastity, in heart, speech, and behaviour.

1 Thessalonians 4:4-5. That every one of you should know how to possess his vessel in sanctification and honour; not in the lust of concupiscence, even as the Gentiles which know not God.
1 Corinthians 7:2. Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.
Ephesians 5:11-12. And have no fellowship with the unfruitful works of darkness, but rather reprove them. For it is a shame even to speak of those things which are done of them in secret.
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.
Ephesians 4:29. Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers.
Colossians 4:6. Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man.
1 Peter 3:2. While they behold your chaste conversation coupled with fear.

Westminster Project - See John Flavel for more thoughts on the seventh commandment