Q: Which is the third commandment?
A: The third commandment is, Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that taketh his name in vain.

Q: What is required in the third commandment?
A: The third commandment requireth the holy and reverent use of God’s names, titles, attributes, ordinances, word, and works.

Q: What is forbidden in the third commandment?
A: The third commandment forbiddeth all profaning or abusing of any thing whereby God maketh himself known.

Q: What is the reason annexed to the third commandment?
A: The reason annexed to the third commandment is, That however the breakers of this commandment may escape punishment from men, yet the Lord our God will not suffer them to escape his righteous judgment.

(Questions LIII, LIV, LV, and LVI from the Westminster Shorter Catechism).