And thou shalt set bounds unto the people round about, saying, Take heed to yourselves, that ye go not up into the mount, or touch the border of it: whosoever toucheth the mount shall be surely put to death: Thou shalt set bounds - Whether this was a line marked out on the ground, beyond which they were not to go, or whether a fence was actually made to keep them off, we cannot tell; or whether this fence was made all round the mountain, or only at that part to which one wing of the camp extended, is not evident.
This verse strictly forbids the people from coming near and touching Mount Sinai, which was burning with Fire. The words therefore in Exodus 19:15, אל תגשו אל אשה al tiggeshu el ishshah, come not at your wives, seem rather to mean, come not near unto the Fire; especially as the other phrase is not at all probable: but the fire is, on this occasion, spoken of so emphatically (see Deuteronomy 5:4, Deuteronomy 5:5, Deuteronomy 5:22-25) that we are naturally led to consider אשה ishshah here as האש ha-esh transposed, or to say, with Simon in his Lexicon, אשה faem, idem quod masc. אש ignis. So among other instances, we have אבר and אברה a wing; אור and אורה light; אמץ and אמצה strength; and אמר and אמרה a speech - Burt. See Kennicott's Remarks.
Whosoever toucheth the mount shall be surely put to death - The place was awfully sacred, because the dreadful majesty of God was displayed on it. And this taught them that God is a consuming fire, and that it is a fearful thing to fall into the hands of the living God.