“Moses reported the statement of the people to the Lord” (Exodus 19:8) – at that moment, the Holy One blessed be He sought to give them the Torah and to speak with them, but Moses was standing [on the mountain]. The Holy One blessed be He said: What shall I do about Moses? Rabbi Levi said: This is analogous to a king who sought to issue a proclamation without the input of his chief official. He said to him: ‘Do such and such.’
He said to him: ‘It is already done.’ He then said to him: ‘Go and summon so-and-so the adviser and let him come with you.’ When he went, the king did what he sought to do. So too, the Holy One blessed be He sought to give the Ten Commandments.
Moses was standing to His side. The Holy One blessed be He said: When I reveal the firmament to them and say: “I am the Lord your God” (Exodus 20:2), they will say: ‘Who spoke; was it the Holy One blessed be He or Moses?’ Rather, let Moses descend, and afterward I will say: “I am the Lord your God.” So, the Holy One blessed be He said to Moses: “Go to the people and sanctify them today and tomorrow, and they shall wash their garments” (Exodus 19:10).
He said to Him: ‘I already sanctified them,’ as it is stated: “As you have warned us, saying: [Demarcate the mountain and sanctify it]” (Exodus 19:23). He said to him: “Go, descend, and you shall ascend and Aaron with you” (Exodus 19:24). When Moses descended, the Holy One blessed be He revealed Himself, as it is stated: “Moses descended to the people” (Exodus 19:25), [and] immediately, “God spoke.”