12 You shall set bounds to the people all around, saying, ‘Be careful that you don’t go up onto the mountain, or touch its border. Whoever touches the mountain shall be surely put to death. 13 No hand shall touch him, but he shall surely be stoned or shot through; whether it is animal or man, he shall not live.’ When the trumpet sounds long, they shall come up to the mountain.” Exodus 19:12-13WEB
This passage contains a negative command, directed toward Israel through Moses: "Put a boundary around the mountain, and let no one go up onto the mountain or touch it. If anyone touches it, he shall be put to death by stoning or shooting, and no hand shall touch him".
The command was carried out by Israel, who enforced the rules as stated. The command finds its fulfillment in Jesus Christ, who enables us to approach the throne of God freely and with confidence (Hebrews 4:16, Ephesians 3:12).
Notes on Interpretation/Application
It's noteworthy that a ranged execution (stoning or shooting) is specified, and that the body is not to be touched afterward. This may be to prevent people from committing the same sin (touching the mountain) in order to procure the body or perform the execution.