Exodus 19:20-22

Wycliffe Bible

²⁰ and the Lord came down on the hill of Sinai, in that top of the hill (and the Lord came down on Mount Sinai, onto the top of the mountain), and he called Moses (up) to the top thereof. And when he had gone up thither,

²¹ the Lord said to him, Go thou down, and witness thou to the people, lest peradventure it will pass [over] the terms to see the Lord (lest they pass over the boundary to see the Lord), and [a] full great multitude thereof perish;

²² and [the] priests, that nigh to the Lord, be they hallowed, lest I smite them (or I shall strike them down).