Exodus 19:3, 20, 23

And Moses went up unto God, and Jehovah called unto him out of the mountain, saying, Thus shalt thou say to the house of Jacob, and tell the children of Israel

And Jehovah came down upon mount Sinai, to the top of the mount: and Jehovah called Moses to the top of the mount; and Moses went up.

And Moses said unto Jehovah, The people cannot come up to mount Sinai: for thou didst charge us, saying, Set bounds about the mount, and sanctify it.