But, before I proceed directly to the prosecution of this point, it will be proper to clear this precept of our LORD from a misrepresentation that has been put on it by some, who infer from hence, that our Saviour prohibits swearing before a magistrate, when required on a solemn and proper occasion. But that all swearing is not absolutely unlawful for a christian, is evident from the writings of St. _Paul_, whom we often find upon some solemn occasions using several forms of imprecation, as, “I call GOD to witness;” “GOD is my judge;” “By your rejoicing in CHRIST JESUS,” and such like. And that our Saviour does by no means forbid swearing before a magistrate, in the words now before us, is plain, if we consider the scope and design he had in view, when he gave his disciples this command. Permit me to observe to you then, that our blessed master had set himself, from the 27th verse of the chapter, out of which the text is taken, to vindicate and clear the moral law from the corrupt glosses and misconstruction of the _Pharisees_, who then sat in _Moses_’s chair, but were notoriously faulty in adhering too closely to the literal expression of the law, without ever considering the due extent and spiritual meaning of it. Accordingly they imagined, that because GOD had said, “Thou shalt not commit adultery,” that therefore, supposing a person was not guilty of the very act of adultery, he was not chargeable with the breach of the seventh commandment. And likewise in the matter of swearing, because GOD had forbidden his people, in the books of _Exodus_ and _Deuteronomy_, “to take his name in vain,” or to swear falsely by his name; they therefore judged it lawful to swear by any creature in common discourse, supposing they did not directly mention the name of GOD. Our blessed Saviour therefore, in the words now before us, rectifies this their mistake about swearing, as he had done in the verses immediately foregoing, concerning adultery, and tells the people, that whatever allowances the _Pharisees_ might give to swear by any creature, yet he pronounced it absolutely unlawful for any of his followers to do so. “You have heard, that it has been said by them of old time,” (namely, by the _Pharisees_ and teachers of the _Jewish_ law) “Thou shalt not forswear thyself, but perform unto the LORD thine oaths: but I say unto you,” (I who am appointed by the Father to be the great prophet and true law-giver of his church) “Swear not at all, (in your common conversation) neither by heaven for it is GOD’s throne; (and therefore to swear by that, is to swear by Him that sits thereon) neither by the earth, for it is his foot-stool; nor 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 communications (which plainly shews that CHRIST is here speaking of swearing, not before a magistrate, but in common conversation) let your communication be yea, yea; nay, nay, (a strong affirmation or negation at the most); for whatsoever is more than this, cometh of evil;” that is, cometh from an evil principle, from the evil one, the devil, the author of all evil.
Which by the way, methinks, should be a caution to all such persons, who, though not guilty of swearing in the gross sense of the word, yet attest the truth of what they are speaking of, though ever so trifling, by saying, Upon my life,――as I live,――by my faith,――by the heavens, and such like: which expressions, however harmless and innocent they may be esteemed by some sorts of people, yet are the very oaths which our blessed LORD condemns in the words immediately following the text; and persons who use such unwarrantable forms of speaking, must expect to be convicted and condemned as swearers, at our Saviour’s second coming to judge the world.
But to return: It appears then from the whole tenor of our Saviour’s discourse, that in the words of the text he does by no means disannul or forbid swearing before a magistrate (which, as might easily be shewn, is both lawful and necessary) but only profane swearing in common conversation; the heinousness and sinfulness of which I come now, more immediately to lay before you.