On dishonest casuistry. The lax moralists of that time invented ways of evading the obligation of truthfulness, by saying that certain forms of swearing were binding and others not. Thus an oath by the Temple or the altar might be broken without sin, but not an oath by the gold of the Temple, or by the gift on the altar. Such refinements were a direct encouragement to dishonesty and untruthfulness, and our Lord denounced them with terrible severity, declaring that a man's word or oath, in whatever words expressed, is absolutely binding. The lesson here taught is truthfulness and honesty in general, as well as the sanctity of oaths. Christ's teaching here is not inconsistent with Matthew 5:34, where from a higher ideal standpoint He forbids oaths altogether.
Related Commentaries of Matthew 23:16
Matthew 23:16-22
16 Woe unto you, ye blind guides, which say, Whosoever shall swear by the temple, it is nothing; but whosoever shall swear by the gold of the temple, he is a debtor!
17 Ye fools and blind: for whether is greater, the gold, or the temple that sanctifieth the gold?
18 And, Whosoever shall swear by the altar, it is nothing; but whosoever sweareth by the gift that is upon it, he is guilty.b
19 Ye fools and blind: for whether is greater, the gift, or the altar that sanctifieth the gift?#rl
20 Whoso therefore shall swear by the altar, sweareth by it, and by all things thereon.
21 And whoso shall swear by the temple, sweareth by it, and by him that dwelleth therein.#rl
22 And he that shall swear by heaven, sweareth by the throne of God, and by him that sitteth thereon.