Exod 19:22-24

22Even the priests who approach the Lord must consecrate themselves or the Lord will break out against them.”23Moses said to the Lord, “The people are not permitted to come up to Mount Sinai; for you yourself warned us, saying, ‘Set limits around the mountain and keep it holy.’ ”24The Lord said to him, “Go down, and come up bringing Aaron with you; but do not let either the priests or the people break through to come up to the Lord; otherwise he will break out against them.”