Albert Barnes Commentary Exodus 19:12

"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:" — Exodus 19:12 (ASV)

Set bounds unto the people - The low line of alluvial mounds at the foot of the cliff of Ras Safsafeh exactly corresponds to the bounds which were to keep the people from touching the mount; but the bounds spoken of here were to be set up by Moses.