12 Mark off a boundary all around the mountain. Warn the people, 'Be careful! Do not go up on the mountain or even touch its boundaries. Anyone who touches the mountain will certainly be put to death. 13 No hand may touch the person or animal that crosses the boundary; instead, stone them or shoot them with arrows. They must be put to death.' However, when the ram's horn sounds a long blast, then the people may go up on the mountain. "
Matthew Henry's Commentary on Exodus 19:12-13
Commentary on Exodus 19:9-15
(Read Exodus 19:9-15)
The solemn manner in which the law was delivered, was to impress the people with a right sense of the Divine majesty. Also to convince them of their own guilt, and to show that they could not stand in judgment before God by their own obedience. In the law, the sinner discovers what he ought to be, what he is, and what he wants. There he learns the nature, necessity, and glory of redemption, and of being made holy. Having been taught to flee to Christ, and to love him, the law is the rule of his obedience and faith.