Westminster Shorter Catechism Q&A 70-72
Q. 70. Which is the seventh commandment?
A. The seventh commandment is, Thou shalt not commit adultery.
Q. 71. What is required in the seventh commandment?
A. The seventh commandment requireth the preservation of our own and our neighbor's chastity, in heart, speech and behavior.
Q. 72. What is forbidden in the seventh commandment?
A. The seventh commandment forbiddeth all unchaste thoughts, words and actions.