Exodus 19:12

And thou shall set bounds to the people round about,.... That is, round about the mountain, by drawing a line, throwing up a foss or ditch, or else by laying up heaps of stones or sand, which might be come at easily, or bushes and branches of trees, which grew thick on the mount, from whence it had its name; but be it what will that were used, these were to signify, that so far the people might go, but no further, which their curiosity might prompt them to:

saying, take heed unto yourselves that ye go not up into the mount; so far were they from being allowed to go up to the top of it, that they were not allowed to ascend it at all, or to go any further than where the ascent or rise began; it was at their peril to ascend, and this was what they were to take heed unto, lest they incurred danger:

or touch the border of it; it being the mountain of God, and relatively holy through his presence on it:

whosoever toucheth the mount shall be surely put to death; which severe law was made to deter them from any attempt to go up the mountain, since it was death even to touch it, see Hebrews 12:18.