Matthew 5:34
But I say to you, Do not take an oath at all, either by heaven, for it is the throne of God. The prohibition is on the entire practice of oath-taking, not merely on false oaths. The reason is that every element of the created order — heaven, earth, Jerusalem, one's own head — belongs to God, making any oath sworn by any of them an implicit oath by God. The attempt to distinguish between binding and non-binding oaths based on what is sworn by is revealed as evasion: there is no created thing that stands outside God's sovereignty that could be sworn by without invoking God.