Or HaChaim on Exodus 19:23/אור החיים על שמות י״ט:כ״ג

1 ויאמר משה…לא יוכל העם, Moses said…"the people are unable, etc." What exactly was the distance between Moses and G'd so that G'd had to tell Moses again in verse 24 to descend and warn the people? Why was G'd's previous directive in verse 21 not sufficient? Moses himself tells G'd that there is no need for any new directive, the previous directive having been sufficient to ensure the people would not breach G'd's warning to establish a fence around the Mountain and to sanctify the people.

2It would appear that originally G'd ordered the people in a general directive neither to ascend nor to touch the Mountain. The Torah also stated in verse 22 that the priests who are normally allowed closer to sacred sites must not approach the Mountain. Subsequently, in verse 24 G'd told Moses that the priests should sanctify themselves. G'd was afraid that the Israelites would apply a method known as דבר שהיה בכלל ויצא מן הכלל ללמד על הכלל יצא, that if something had previously been part of a general rule and was singled out by the Torah by name, the reason is that the special rule now applied to this "something" will also be applied generally forthwith. Initially, both the priests, the people, and even Aaron were included in the prohibition to ascend the Mountain or to touch it. As soon as the priests were mentioned separately such as in 19,22 as being normally permitted to approach G'd, this implied they could at least touch it also in this case. In view of the rule cited above about כל היוצא מן הכלל, the people would now also be allowed to touch the base of the Mountain. While it is true that since the Torah had not been given yet, the rule we quoted was not yet in effect, the fact remains that since the rule is based on logic, some intelligent Jew might have figured it out already before the Torah was actually handed down to the people. Even assuming that no one could have figured out this rule, G'd desires justice and righteousness and He would not apply the death penalty to a person who touched the lower part of the Mountain when his counterpart the priest would not be punished for doing the same thing by reason of his being a priest. In order to prevent such a potential miscarriage of justice, G'd told Moses to descend from the Mountain and warn the people (the non-priests) not to touch any part of the Mountain. The effect of this warning was to invalidate the rule about כל היוצא מן הכלל which we explained earlier. Moses had not understood this immediately because G'd had not yet revealed to him the rule about כל היוצא מן הכלל as well as the other principles which guide us when interpreting the written Torah. Moses thought that the partial relaxation of the prohibition applied only to Aaron and the priests whereas the people were forbidden to touch even the base of the Mountain. He could not understand why such a repeated warning was necessary, seeing G'd had already warned the people not to ascend the Mountain or to touch it. G'd therefore told him that only he and Aaron were allowed to ascend any part of the Mountain. Moses was to warn the people that the very places he and Aaron were allowed to ascend would be out of bounds to the people at large. We see that G'd had to spell out a prohibition where logic would have dictated that there was no prohibition or that such a prohibition had been relaxed.

3According to what we have explained, the word הנגשים in verse 22 refers to areas in which the priests were permitted access once the Tabernacle would become operational. In short, G'd told Moses that there would be three different areas on the Mountain. The people could not ascend any part, Aaron could accompany Moses part of the way; the upper regions of the Mountain were accessible to Moses only. The new element in G'd's second warning is that He permitted Aaron to ascend part of the Mountain, something that had been excluded by the wording of the previous warning.

4Another reason G'd issued a second warning to the people was that the first warning did not include a time frame, i.e. when it would begin to be effective. Although the Torah had spoken about "three days," those days had not been specifically linked to the restrictions of ascending the Mountain beginning on the third day. This is why G'd told Moses as soon as He had descended on to the Mountain that he should descend and tell the people that the restrictions concerning ascent of the Mountain were effective forthwith. We need to study Moses' reply. Perhaps he had thought that the prohibition of ascending the Mountain became effective already at the moment G'd had issued it seeing G'd had not said specifically: "do not touch the Mountain on the second day," or something similar. He had been wrong on that count, and this explains why G'd now had to send him down to tell the people that the prohibition of which they had been told was now in effect. When G'd had issued the warning the first time He had said that anyone violating it would be stoned to death, i.e. would be punished by a human tribunal. G'd now repeated the warning to make it plain that if someone would violate the prohibition in such a way that no judicial action could be taken against him such a person would nonetheless be punished by heaven. The reason the Torah phrased the potential violation in the plural was that even if all the people would violate the prohibition this would not save them from the penalty G'd would impose.