“You shall not take the name of the LORD your God in vain, for the LORD will not leave him unpunished who takes His name in vain.” Deuteronomy 5:11 (NASB)
“Holy and reverend is His name” (Psalm 111:9). God’s name is to be held in reverence, as God Himself is. “In vain” represents a Hebrew expression that has varied meanings and can apply to much more than just swearing. This Commandment is violated when His name is used lightly, frivolously, and with no meaning or purpose at all; it is violated when one swears profanely by God; it is violated when one swears falsely by God; and it is violated when one uses God’s name as a mere expression of surprise, alarm, or indignation.
Someone may say, “I don’t mean anything by it,” to excuse such frivolous use of God’s name. But “without meaning” is one of the meanings of “in vain.” The name of the Lord ought never to be spoken or written without reverence.
“For whoever gives you a cup of water to drink in My name, because you belong to Christ, assuredly, I say to you, he will by no means lose his reward.”
Marl 9:41 (NKJV)