CCC 2152
Life in Christ›SECTION TWO THE TEN COMMANDMENTS›CHAPTER ONE YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR MIND›II. Taking the Name of the Lord in Vain
A person commits perjury when he makes a promise under oath with no intention of keeping it, or when after promising on oath he does not keep it. Perjury is a grave lack of respect for the Lord of all speech. Pledging oneself by oath to commit an evil deed is contrary to the holiness of the divine name.