It is very sad that there are many professing Christians that swear badly. They even go to church on Sunday and swear in the parking lot.
But Jesus and his apostles did NOT swear. How do I know? There is no statement that directly says not to cuss, but there is powerful circumstantial evidence.
After Christ was arrested, Peter was warming himself by a fire and someone said that Peter was with Jesus:
Then began he to curse and to swear, saying, I know not the man. And immediately the cock crew. (Matthew 26:74) (KJV)
Now, why did he curse and swear? I believe it was because Jesus and his disciples did NOT do so. Peter was trying to show that he was not one of Jesus’ disciples.
For a Christian to swear when those around know that the person claims to be a Christian, the person swearing is stating boldly, “I am a hypocrite.” It is a smear upon Christianity and lowers the view of all Christians in the eyes of those who see and hear the Christian swearing.