Or if a soul swear,.... A rash or vain oath:pronouncing with his lips; not in his heart, as Jarchi notes; not saying within himself that he would do this, or that, or the other thing, but expressing his oath plainly and distinctly, with an audible voice:to do good, or to do evil; which was either impossible or unlawful for him to do; whether the good or evil he swears to do is to himself or to another; whether he swears to do good to himself, and evil to another, or, good to another, and evil to himself, see Ps 15:4.
The Targum of Jonathan paraphrases it,"whatsoever a man expresses, whether of anything present or future;''as if he swears he has done such and such a thing, whether good or evil; or that he will do it, be it what it will, and it is not in the power of his hands to do it, or, if he did it, it would be doing a wrong thing:whatsoever [it be] that a man shall pronounce with an oath, and it be hid from him; he has forgot that he ever swore such an oath:and when he knoweth [of it], then he shall be guilty in one of these; when he is told of it, and it is made clearly to appear to him, that he did at such a time, and in such a place, deliver out a rash oath concerning this, or the other thing, then he shall be chargeable with guilt in one of these; either in rashly swearing to do good when it was not in his power, or to do evil, which would have been unlawful.
The Targum of Jonathan is,"if he knows that he has falsified, and repents not, he is guilty.'