But above all, my brethren, do not swear, either by heaven or by earth or with any other oath; but your yes is to be yes, and your no, no, so that you may not fall under judgment.

• James 1:26
  If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless.
• James 3:5-12
  So also the tongue is a small part of the body, and yet it boasts of great things. See how great a forest is set aflame by such a small fire! And the tongue is a fire, the very world of iniquity; the tongue is set among our members as that which defiles the entire body, and sets on fire the course of our life, and is set on fire by hell. For every species of beasts and birds, of reptiles and creatures of the sea, is tamed and has been tamed by the human race. But no one can tame the tongue; it is a restless evil and full of deadly poison. With it we bless our Lord and Father, and with it we curse men, who have been made in the likeness of God; from the same mouth come both blessing and cursing. My brethren, these things ought not to be this way. Does a fountain send out from the same opening both fresh and bitter water? Can a fig tree, my brethren, produce olives, or a vine produce figs? Nor can salt water produce fresh.
• Exodus 20:7
  “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.”
• Leviticus 5:1-5
  Now if a person sins after he hears a public adjuration to testify when he is a witness, whether he has seen or otherwise known, if he does not tell it, then he will bear his guilt. … Or if a person swears thoughtlessly with his lips to do evil or to do good, in whatever matter a man may speak thoughtlessly with an oath, and it is hidden from him, and then he comes to know it, he will be guilty in one of these. So it shall be when he becomes guilty in one of these, that he shall confess that in which he has sinned.
• Numbers 30:2
  If a man makes a vow to the LORD, or takes an oath to bind himself with a binding obligation, he shall not violate his word; he shall do according to all that proceeds out of his mouth.
• Matthew 5:33-37
  “Again, you have heard that the ancients were told, ‘YOU SHALL NOT MAKE FALSE VOWS, BUT SHALL FULFILL YOUR VOWS TO THE LORD.’ But I say to you, make no oath at all, either by heaven, for it is the throne of God, or by the earth, for it is the footstool of His feet, or by Jerusalem, for it is THE CITY OF THE GREAT KING. Nor shall you make an oath by your head, for you cannot make one hair white or black. But let your statement be, ‘Yes, yes’ or ‘No, no’; anything beyond these is of evil.