Be Ready and the Call to Separate Before Sinai

"And he sanctified the people" (Exodus 19:14): he prepared them, and they washed their garments, purified themselves, and changed their clothing. "And he said to the people, Be ready for three days" (Exodus 19:15). But we have not heard that the Omnipresent told Moses to separate from women; we have only "Be ready." Above it says, "and let them be ready" (Exodus 19:11). This is an analogy of equal expressions [gezeira shava]: just as "be ready" stated here means to separate from women, so too "ready" stated there means to separate from women.