Weekly Catechism for 2018 (Heidelberg 1563): Lord’s Day 36
99. What is required in the third commandment?
That we must not by cursing, or by false swearing, nor yet by unnecessary oaths, profane or abuse the name of God; nor even by our silence and connivance be partakers of these horrible sins in others; and in sum, that we use the holy name of God no otherwise than with fear and reverence, so that He may be rightly confessed and worshiped by us, and be glorified in all our words and works.
100. Is then the profaning of God’s name by swearing and cursing so grievous a sin that His wrath is kindled against those also who seek not, as much as in them lies, to hinder and forbid the same?
Yes truly: for no sin is greater, or more provoking to God than the profaning of His name. Wherefore He even commanded it to be punished with death.