Question: What does the Bible say about swearing?
Answer: It depends on what you mean by swearing. If by swearing you mean using ugly words in order to shock or intimidate people, there is very little specifically said about that in the Bible. Proverbs speaks a lot about the way we abuse words generally (Proverbs 11:9; 12:18; 18:21 to name a few).
If you are talking about making an oath in God’s name, the Bible says a lot about that kind of swearing. The command against using the Lord’s name in vain in Exodus 20:7 is a command against swearing an oath in Yahweh’s name and then not keeping it. The typical oath or swearing in this case would be something like, “May God strike me dead if I am telling a lie.” If you violate that oath, you have brought God’s integrity into the mix and abused it. Of course Jesus taught us, in the sermon on the mount in Matthew 5:33-37, that we ought to simply tell the truth and not swear oaths, in recognition of the fact that our integrity needs to come from our hearts and not some external threat of punishment.