Exodus 19:10-15 "And the LORD said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes, and be ready against the third day: for the third day the LORD will come down in the sight of all the people upon mount Sinai. And thou shalt set bounds unto the people round about, saying, Take heed to yourselves, that ye go not up into the mount, or touch the border of it: whosoever toucheth the mount shall be surely put to death: There shall not an hand touch it, but he shall surely be stoned, or shot through; whether it be beast or man, it shall not live: when the trumpet soundeth long, they shall come up to the mount. And Moses went down from the mount unto the people, and sanctified the people; and they washed their clothes. And he said unto the people, Be ready against the third day: come not at your wives."
Moses called all the elders of the children of Israel together. When they were assembled, he told them plainly all that the LORD had said. The people responded that they would do everything God had commanded of them. God then told Moses that He would come to him in a thick cloud and speak so that the children of Israel might hear His voice and believe the words that Moses told them.
The LORD commanded Moses to instruct the people to sanctify (wash) themselves and their garments. Once washed, they were to abstain from their natural desires, even lawful ones (including intimacy with a spouse) so their whole attention was fixed on the LORD. They were to be prepared in three days to see the LORD descend upon mount Sinai. The children of Israel had to be clean before they could see the LORD come in such a manner. There were boundaries set for them concerning His coming to mount Sinai.
Whether man or beast, they were to take heed to themselves not to touch the mountain. The penalty for touching the mountain was immediate death. They could not touch the mountain and live. At the same time, they could not refuse to come to the border of the mountain when the trumpet sent out the call.
This was a time of fear and trembling, even as it should be for us today when we are faced with God’s righteous law and our inability to keep it. Glory to God that there was another “third day” event coming that would seal for us the privilege of entering into God’s presence with joy. Trusting in our own strength to touch the law of God is death because we cannot keep it. This death Jesus bore for us because we could not bear it ourselves. In Jesus, we are not come to Mount Sinai, but instead we are called to Mount Zion and the city of the living God (Hebrews 12:18-24)!