Question 59: Which is the third commandment?
Answer: 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.”
Scripture: Exodus 20:7.
Question 60: What is required in the third commandment?
Answer: The third commandment requires the holy and reverent use of God’s name, titles, attributes, ordinances, words, and works.
Question 61: What is forbidden in the third commandment?
Answer: The third commandment forbids all profaning and abusing of anything whereby God makes himself known.
Question 62: What is the reason annexed to the third commandment?
Answer: 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.
The Baptist Catechism above was adapted by John Piper. This post in its entirety can be found at http://www.desiringgod.org/articles/a-baptist-catechism