But above all, my brothers, do not swear, either by heaven or by earth or by any other oath, but let your “yes” be yes and your “no” be no, so that you may not fall under condemnation. (ESV)
Does it matter what we say? There seems to be a lack of truthfulness and integrity in many people when it comes to what they say. Some would say about a politician that you know he is lying because his lips are moving. God cares very much what we say. We are told not to swear. Now, this is going to need a bit more clarification.
By telling us not to swear, James is not talking about some of the crass cuss words that may come to your mind. He is talking about making promises to another person that you have no intention of keeping. By doing so, you are lying to your brother. This is a practice that was common in the Jewish community at the time James wrote this epistle.
"As Jesus did before him (Matt. 5:33–36; 23:16–22), James condemned the contemporary Jewish practice of swearing false, evasive, deceptive oaths by everything other than the name of the Lord (which alone was considered binding)."
- Dr. John MacArthur, MacArthur Study Bible Notes
Perhaps you have known someone who claimed to be a fellow believer in Jesus Christ who made promises to you, but never kept them. This should never be the case. I know people who will not have a Christian work on their car or do construction work for them because they do not trust them. This is the opposite of how things should be.
If we truly belong to Christ we should be the most honest people anyone could meet. As James says, Our "yes" should mean "yes," and our "no" should mean "no." We are to reflect the very nature of God. One thing we know for certain about God is that he cannot lie. His Word is eternal and perfect. We can always trust him. We are to be like him.
Do you find yourself being dishonest with others? Ask the Lord to forgive you. He will help you to live a life of honesty and truthfulness. This will please him and bless others.