Exodus 19:3, 20, 23

while Moses went up to God. The LORD called to him out of the mountain, saying, “Thus you shall say to the house of Jacob, and tell the people of Israel

The LORD came down on Mount Sinai, to the top of the mountain. And the LORD called Moses to the top of the mountain, and Moses went up.

And Moses said to the LORD, “The people cannot come up to Mount Sinai, for you yourself warned us, saying, ‘Set limits around the mountain and consecrate it.’”