What is the precise force of this prohibition? The word used is ambiguous: sometimes it must be rendered as here, as in the verses “_Vain_ is the help of man,” and “Except the Lord build the house, their labour is but _vain_ that build it” (Psalm cviii. 12, cxxvii. 1). But sometimes it clearly means false, as in the texts “Thou shalt not raise a _false_ report,” and “swearing _falsely_ in making a covenant” (Exod. xxiii. 1; Hos. x. 4). Yet again, it hangs midway between the two ideas, as when we read of “_lying_ vanities,” and again, “trusting in vanity and speaking _lies_” (Psalm xxxi. 6; Isa. lix. 4). In favour of the rendering “falsely” it is urged that our Lord quotes it as “said to them of old time ‘Thou shalt not forswear thyself’” (Matt. v. 33). But it is by no means clear that He quotes this text: the citation is closer to the phraseology of Lev. xix. 12, and it is found in a section of the Sermon which does not confine its citations to the Decalogue (cf. ver. 38). The Authorised rendering seems the more natural when we remember that civic duty had not yet come upon the stage. When we have learned to honour only one God, and not to degrade nor materialise our conception of Him, the next step is to inculcate, not yet veracity toward men when God has been invoked, but reverence, in treating the sacred name. We have already seen the miserable superstitions by which the Jews endeavoured to satisfy the letter while outraging the spirit of this precept. In modern times some have conceived that all invocation of the Divine Name is unlawful, although St. Paul called God for a witness upon his soul, and the strong angel shall yet swear “by Him Who liveth for ever and ever” (2 Cor. i. 23; Rev. x. 6). As it is not a temple but a desert which no foot ever treads, so the sacred name is not honoured by being unspoken, but by being spoken aright. Swearing is indeed forbidden, where it has actually disappeared, namely, in the mutual intercourse of Christian people, whose affirmation should suffice their brethren, while the need of stronger sanctions “cometh of evil,” even of the consciousness of a tendency to untruthfulness, which requires the stronger barrier of an oath. But our Lord Himself, when adjured by the living God, responded to the solemn authority of that adjuration, although His death was the result.