Exodus 19:21-25

and the LORD said to him, “Go down and warn the people so they do not force their way through to see the LORD and many of them perish. Even the priests, who approach the LORD, must consecrate themselves, or the LORD will break out against them.” Moses said to the LORD, “The people cannot come up Mount Sinai, because you yourself warned us, ‘Put limits around the mountain and set it apart as holy.’ ” The LORD replied, “Go down and bring Aaron up with you. But the priests and the people must not force their way through to come up to the LORD, or he will break out against them.” So Moses went down to the people and told them.