99. What is required in the third commandment?
That we must not by cursing,1 or by false swearing,2 nor yet by unnecessary oaths,3 profane or abuse the name of God; nor even by our silence and connivance be partakers of these horrible sins in others; and in summary, that we use the holy name of God in no other way than with fear and reverence,4 so that He may be rightly confessed5 and worshiped6 by us, and be glorified in all our words and works.7
 Lev. 24:10–16.  Lev. 19:12.  Matt. 5:37; Jas. 5:12.  Isa. 45:23.  Matt. 10:32.  1 Tim. 2:8.  Rom. 2:24; 1 Tim. 6:1; Col. 3:16–17; *1 Pet. 3:15.
100. Is the profaning of God’s name, by swearing and cursing, so grievous a sin that His wrath is kindled against those also who do not help as much as they can to hinder and forbid it?
Yes, truly,1 for no sin is greater and more provoking to God than the profaning of His name; wherefore He even commanded it to be punished with death.2
 Lev. 5:1  Lev. 24:15–16; *Lev. 19:12; *Prov. 29:24–25.
101. But may we swear reverently by the name of God?
Yes, when the magistrate requires it, or when it may be needful otherwise, to maintain and promote fidelity and truth to the glory of God and our neighbor’s good; for such an oath is grounded in God’s Word,1 and therefore was rightly used by the saints in the Old and New Testaments.2
 Deut. 10:20; Isa. 48:1; Heb. 6:16.  Gen. 21:24; 31:53–54; Josh. 9:15, 19; 1 Sam. 24:22; 1 Kgs. 1:29; Rom. 1:9.
102. May we swear by “the saints” or by any other creatures?
No, for a lawful oath is a calling upon God, that He, as the only searcher of hearts, may bear witness to the truth, and punish me if I swear falsely;1 which honor is due to no creature.2
 2 Cor. 1:23.  Matt. 5:34–36; *Jer. 5:7; *Isa. 65:16.