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.
The thick cloud prohibits curious enquiries into secret things and commands awful adoration of what is revealed. God comes down visibly so the people see His glory and are convinced He is among them. This honours Moses especially: when they hear God speak to him and see it with their own eyes, they will believe him forever.
AI summary
Commenting on Exodus 19:9-15
The third day here means three days from now, the sixth day of the month, when the Law was given, this the Jews universally agree on. The Lord's descent must be understood consistently with His omnipresence; it means a visible display of His power and a sensible token of His presence, not a change of location. He will appear in thick cloud and fire, visible to all the people, though His form remains unseen.
AI summary
God prepares the people through sanctification: washing of body and clothes, and abstaining from conjugal intercourse because defilement attends it. He sets bounds round the mountain itself with death as the penalty for any who touch even its outermost edge, until the long trumpet blast signals that they may ascend.
AI summary
Commenting on Exodus 19:10-15