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. (James 5:12 ESV)
Have you ever made a promise while crossing your fingers or made an oath to a friend and said, “cross my heart and hope to die”? Those are things I used to do as a little kid. You would cross your fingers when you knew you were going to break your promise (somehow that made it okay to do) and you swore on your life (that’s crossing your heart and hoping to die) when you wanted someone to believe your promise.
People swear or “promise” based on something. They might say, “I swear as sure as I’m standing here” or “I swear on my momma’s grave.” While those are weird things to swear by they reveal something about the person who is swearing…. They normally lie. If people won’t believe what you say, it’s probably because you crossed your fingers one too many times and they are reluctant to trust you. James says that you are not to swear or promise by anything, rather just speak the truth.
Lying is what we do when we don’t trust God. Swearing is what we do when we’ve lied so many times that people won’t believe us… James reminds us not to cross our fingers or swear by anything because someone who trusts God has no reason to lie.