Charles Spurgeon Commentary Matthew 23:20-22

"He therefore that sweareth by the altar, sweareth by it, and by all things thereon. And he that sweareth by the temple, sweareth by it, and by him that dwelleth therein. And he that sweareth by the heaven, sweareth by the throne of God, and by him that sitteth thereon." — Matthew 23:20-22 (ASV)

The Jews invented fantastic forms of swearing in order to evade the use of the divine name. Our Lord therefore next proved the utter failure of all their attempts. Swearing “by the altar” was swearing by all things thereon. An oath “by the temple” was really by him that dwelleth therein. The binding force of the oath could not lie in the mere building, but in the most High God, who condescended to dwell in it.

Many Jews would swear “by heaven,” although they would not call God to be a witness to their adjuration, but Jesus showed that they were doing the very thing they tried to avoid, He that shall swear by heaven, sweareth by the throne of God, and by him that sitteth thereon. The only right course for us is to obey our Lord’s command, I say unto you, swear not at all; neither by heaven; for it is God’s throne: nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King. Neither shalt thou swear by thy head, because thou canst not make one hair white or black. But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.