Right in the middle of Deuteronomy, God promised Israel another mediator “like Moses”. Well, technically, he did it roughly forty years earlier, but Deuteronomy is where we find the details.
Exodus 20 tells the original story of this awesome encounter and its consequences, and Moses repeated it to a new generation of Israelites in Deuteronomy 5. God graciously accommodated a terrified people at Sinai (Horeb), unwilling to continue experiencing the Almighty’s presence directly, when he spoke to them from heaven out of the midst of the fire and gave them the first ‘ten words’ out of many commands.
The people then begged Moses to receive God’s message to them on behalf of the entire nation.