Exodus 19:22-24

22Also let the priests who come near to the Lord aconsecrate themselves, lest the Lord bbreak out against them.” 23And Moses said to the Lord, “The people cannot come up to Mount Sinai, for you yourself warned us, saying, c‘Set limits around the mountain and consecrate it.’” 24And the Lord said to him, “Go down, and come up bringing Aaron with you. But do not let the priests and the people dbreak through to come up to the Lord, lest he break out against them.”
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