Exodus 19:23
And Moses said unto the LORD, The people cannot come up to mount Sinai: for thou chargedst us, saying, Set bounds about the mount, and sanctify it. And Moses said unto the LORD, The people cannot come up to mount Sinai: for thou chargedst us, saying, Set bounds about the mount, and sanctify it.
Moses' reply to the Lord was that the people could not come up to Mount Sinai because bounds had been set about the mount at His charge and it had been sanctified, set apart as holy and consecrated and kept holy. The boundary marked the sacredness of God's presence and protected the people from approaching it, while a thick cloud shielded them from the glory of His presence so they could hear His voice without being destroyed. The setting was the third-day descent of the Lord upon Sinai in fire with thunders and lightnings and thick cloud and an exceeding loud trumpet and smoke as of a furnace and great quaking, giving every evidence that God was in the mount, the God who would not bear iniquity, and the mountain and its created surroundings impressed His majesty and the people's smallness.
The bounds and warning were given to a people delivered from Egyptian slavery so they might be given a knowledge of God as never before and have evidence that He was God. The verse stands soon after the encampment at Sinai when Moses alone climbed the steep and rugged path to the cloud marking the divine presence, and its answer belongs to the Lord's repeated command for Moses to go down and charge the people lest they break through to gaze and many perish and to require the priests who come near to sanctify themselves lest He break forth upon them, followed by the direction to go down and come up with Aaron while priests and people must not break through. This took place where Israel was to be taken into a close and peculiar relation to be incorporated as a church and a nation under divine government, with the promise that if they obeyed His voice and kept His covenant they would be a peculiar treasure above all people and a kingdom of priests and a holy nation, which Moses repeated to the elders and they answered together that all the Lord had spoken they would do, thus entering a solemn covenant pledging to accept Him as ruler and becoming in a special sense subjects of His authority, immediately before the giving of the Ten Commandments.
At Sinai the Lord came down before Israel and drew near to give His law, and the Ten Commandments were spoken there with awe-inspiring authority, with promises for obedience; the laws given there guard against injustice and guide dealings with one another, and Christ was the Teacher who gave these directions. Moses was charged to check that the boundary and the mountain's sanctity were observed before the law was spoken from Sinai. The instruction given at Sinai, in chapter 19 together with chapter 20, is of great importance and should be often repeated and sacredly observed, and remains needed now; obedience to all the commandments is the highest education taught by God rather than by unsanctified human teachers, showing the Lord is the only true God who demands obedience to His word, so that at a time when every device is used to draw people away from truth and righteousness those who stand on the Lord's side keep holy the memorial of creation appointed after six days of creation work, when God blessed the seventh day and sanctified it as a day of rest.