Matthew 5:33-34

33‘You also know the rule that God gave to your ancestors: “If you make a promise to God, you must do what you have said.”

34But what I tell you is this. Do not use any name to make a promise stronger. Do not use the words “by heaven” to make a promise stronger. Heaven is the place where God rules. Do not use the words “by the earth” to make a promise stronger. The earth is the place where God rests his feet.