and Moses went up to God. יהוה called to him from the mountain, saying, “Thus shall you say to the house of Jacob and declare to the children of Israel:

‘You have seen what I did to the Egyptians, how I bore you on eagles’ wings and brought you to Me. Now then, if you will obey Me faithfully and keep My covenant, you shall be My treasured possession among all the peoples. Indeed, all the earth is Mine, but you shall be to Me a kingdom of priests and a holy nation.’ These are the words that you shall speak to the children of Israel.”

And יהוה said to Moses, “I will come to you in a thick cloud, in order that the people may hear when I speak with you and so trust you ever after.” Then Moses reported the people’s words to יהוה,

וגם בך AND IN THEE ALSO [WILL THEY BELIEVE] — The word “also” implies that they will believe also in the prophets who will come after thee (Mekhilta d'Rabbi Yishmael 19:9:1).

את דברי העם וגו׳ THE WORDS OF THE PEOPLE etc. — He said to God: “I have heard from them a reply to this statement — that their desire is to hear the commandments from You and not from me. One who hears from the mouth of a messenger is not the same (in the same position) as one who hears directly from the mouth of the King himself. It is our wish to see our King (cf. Mekhilta d'Rabbi Yishmael 19:9:2).

The Jews did not believe in Moses, our teacher, because of the wonders that he performed. Whenever anyone's belief is based on wonders, [the commitment of] his heart has shortcomings, because it is possible to perform a wonder through magic or sorcery.
All the wonders performed by Moses in the desert were not intended to serve as proof [of the legitimacy] of his prophecy, but rather were performed for a purpose. It was necessary to drown the Egyptians, so he split the sea and sank them in it. We needed food, so he provided us with manna. We were thirsty, so he split the rock [providing us with water]. Korach's band mutinied against him, so the earth swallowed them up. The same applies to the other wonders.
What is the source of our belief in him? The [revelation] at Mount Sinai. Our eyes saw, and not a stranger's. Our ears heard, and not another's. There was fire, thunder, and lightning. He entered the thick clouds; the Voice spoke to him and we heard, "Moses, Moses, go tell them the following:...."
Thus, [Deuteronomy 5:4] relates: "Face to face, God spoke to you," and [Deuteronomy 5:3] states: "God did not make this covenant with our fathers, [but with us, who are all here alive today]."
How is it known that the [revelation] at Mount Sinai alone is proof of the truth of Moses' prophecy that leaves no shortcoming? [Exodus 19:9] states: "Behold, I will come to you in a thick cloud, so that the people will hear Me speaking to you, [so that] they will believe in you forever." It appears that before this happened, they did not believe in him with a faith that would last forever, but rather with a faith that allowed for suspicions and doubts.

Thus, those to whom [Moses] was sent witnessed [his appointment] as a prophet, and it was not necessary to perform another wonder for them. He and they were witnesses, like two witnesses who observed the same event together. Each one serves as a witness to his colleague that he is telling the truth, and neither has to bring any other proof to his collegue.
Similarly, all Israel were witnesses to [the appointment of] Moses, our teacher, at the [revelation] at Mount Sinai, and it was unnecessary for him to perform any further wonders for them.
This concept [is alluded to in the interchange between God and Moses at the revelation of the burning bush]. At the beginning of his prophecy, the Holy One, blessed be He, gave him the signs [and wonders] to perform in Egypt and told him [Exodus 3:18], "And they will listen to your voice."
Moses, our teacher, knew that one who believes [in another person] because of signs has apprehension in his heart; he has doubts and suspicions. Therefore, he sought to be released from the mission, saying: "They will not believe me" [Exodus 4:1], until the Holy One, blessed be He, informed him that these wonders [were intended only as a temporary measure,] until they left Egypt. After they would leave, they would stand on this mountain and all doubts which they had about him would be removed.
[God told him:] Here, I will give you a sign so that they will know that I truly sent you from the outset, and thus, no doubts will remain in their hearts. This is what is meant by [Exodus 3:12]: "This will be your sign that I sent you: When you take the people out of Egypt, you will serve God on this mountain."
Thus, we do not believe in any prophet who arises after Moses, our teacher, because of the wonder [he performs] alone, as if to say: If he performs a wonder we will listen to everything he says. Rather, [we believe him] because it is a mitzvah which we were commanded by Moses who said: If he performs a wonder, listen to him.
Just as we are commanded to render a [legal] judgment based on the testimony of two witnesses, even though we do not know if they are testifying truthfully or falsely, similarly, it is a mitzvah to listen to this prophet even though we do not know whether the wonder is true or performed by magic or sorcery.

Therefore, if a prophet arises and attempts to dispute Moses' prophecy by performing great signs and wonders, we should not listen to him. We know with certainty that he performed those signs through magic or sorcery. [This conclusion is reached] because the prophecy of Moses, our teacher, is not dependent on wonders, so that we could compare these wonders, one against the other. Rather we saw and heard with our own eyes and ears as he did.
To what can this be compared? To witnesses who gave testimony concerning a matter to a man who had observed the situation with his own eyes. He will never listen to them and will know for certain that they are false witnesses.
Therefore, the Torah states (Deuteronomy 13:3-4) that "[Even] if [such] a sign or wonder will come, you should not listen to the words of that prophet." He comes to you with signs and wonders to deny what you saw with your own eyes. We believe in a wonder [as evidence of a prophet's reliability] only because of the mitzvah which Moses commanded us. Therefore, how can a wonder [cause us to] accept this [person] who comes to deny the prophecy of Moses which we saw and heard?