Rebbi (Rabbi Yehudah HaNasi) offers a different solution to the question of how Moses derived the requirement for marital separation before receiving the Torah. Rather than relying on a gezeirah shavah (verbal analogy), Rebbi argues that the answer is embedded in the verse itself: "Go to the people and make them ready today and tomorrow" (Exodus 19:10).
His reasoning is precise. If God had meant only ritual immersion — the standard purification process — then the timeline would not work as stated. A person who immerses becomes ritually pure at sunset of the same day. So if the people immersed on the fifth day of Sivan, they would already be clean by that evening, well in advance of the Torah-giving on the sixth. One day would be sufficient for immersion. Why, then, did God specify "today and tomorrow" — requiring two full days of preparation?
The extra time, Rebbi concludes, can only mean one thing: the days were needed for marital separation, not merely for immersion. Separation requires a waiting period that immersion alone does not. The two-day instruction in the verse is itself the proof that more than immersion was intended.
Rebbi reads the phrase "Go to the people" as further confirmation. "The people" in this context refers to married couples — husband and wife units. God was directing Moses to go specifically to these couples and instruct them to separate for three days in preparation for the revelation. The Torah did not need a second verse or a verbal analogy to establish this requirement. It was written plainly in the original command, visible to anyone who read the timeline carefully.