Adam Clarke's Bible Commentary Verse 9. A thick cloud] This is interpreted by ver. 18: And Mount Sinai was altogether on a SMOKE-and the SMOKE thereof ascended as the SMOKE of a furnace; his usual appearance was in the cloudy pillar, which we may suppose was generally clear and luminous.
That the people may hear] See the note on "Exodus xv. 9". The Jews consider this as the fullest evidence their fathers had of the Divine mission of Moses; themselves were permitted to see this awfully glorious sight, and to hear God himself speak out of the thick darkness: for before this, as Rabbi Maymon remarks, they might have thought that Moses wrought his miracles by sorcery or enchantment; but now, hearing the voice of God himself, they could no longer disbelieve nor even doubt.
Matthew Henry Commentary
Verses 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 the of their own guilt, and to show that they could not stand in judgmen before God by their own obedience. In the law, the sinner discover 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.
Original Hebrew ויאמר559 יהוה3068 אל413 משׁה4872 הנה2009 אנכי595 בא935 אליך413 בעב5645 הענן6051 בעבור5668 ישׁמע8085 העם5971 בדברי1696 עמך5973 וגם1571 בך יאמינו539 לעולם5769 ויגד5046 משׁה4872 את853 דברי1697 העם5971 אל413 יהוה׃3068