Rabbi Yehudah explains a remarkable exchange between God and Moses at Sinai. God told Moses: I will speak something to you, and you will return an answer to Me, and then I will acknowledge your answer publicly. The purpose of this choreographed exchange was not that God needed Moses's input — it was to build Moses's authority in the eyes of Israel.
The sequence unfolds across several verses in (Exodus 19). God speaks to Moses in verse 21. Moses responds in verse 23. God acknowledges Moses's response in verse 24. And the payoff comes in verse 9: "so that the people hear when I speak with you, and in you, too, will they believe forever."
The Mekhilta is revealing something extraordinary about how prophetic authority is established. God did not simply declare Moses to be His prophet and demand that the people accept it. Instead, He staged a public conversation — visible and audible to the entire nation — in which Moses spoke and God answered. The people could see with their own eyes that God and Moses were engaged in genuine dialogue.
This was strategic. Once the Israelites witnessed God responding directly to Moses, they would trust Moses for the rest of his career as a prophet. Every future commandment Moses delivered, every law he transmitted, every instruction he gave would carry the weight of that public demonstration at Sinai. The moment was designed to create permanent credibility.
The phrase "and in you, too, will they believe forever" is the key. Sinai was not just about receiving the Torah. It was about establishing the mechanism by which all future Torah would be transmitted — through Moses, whose authority God personally validated before the entire nation.