And so terrible was the sight, that Moses said - This is not recorded in the account of the giving of the Law in Exodus, and it has been made a question on what authority the apostle made this declaration respecting Moses. In Deuteronomy 9:19, Moses indeed says, of himself, after he had come down from the mountain, and had broken the two tables of stone that were in his hand, that he was greatly afraid of the anger of the Lord on account of the sin of the people. "I was afraid of the anger and hot displeasure wherewith the Lord was wroth against you to destroy you;" and it has been supposed by many that this is the passage to which the apostle here alludes. But it is very evident that was spoken on a different occasion from the one which is referred to in the passage before us. That was after the Law was promulgated, and Moses had descended from the mount; and it was not said in view of the terrors of the scene when the Law was given, but of the apprehension of the wrath of God against the people for their sin in making the golden calf.
I know not how to explain this, except by the supposition that the apostle here refers to some tradition that the scene produced this effect on his mind. In itself it is not improbable that Moses thus trembled with alarm (compare Exodus 19:16), nor that the remembrance of it should have been handed down among the numerous traditions which the Jews transmitted from age to age. There must have been many things that occurred in their journey through the wilderness which are not recorded in the Books of Moses. Many of them would be preserved naturally in the memory of the people, and transmitted to their posterity; and though those truths might become intermingled with much that was fabulous, yet it is not irrational to suppose that an inspired writer may have adduced pertinent and true examples from these traditions of what actually occurred. It was one method of preserving "the truth," thus to select such instances of what actually took place from the mass of traditions which were destined to perish, at would be useful in future times. The circumstance here mentioned was greatly suited to increase the impression of the sublimity and fearfulness of the scene. Moses was accustomed to commune with God. He had met him at the "bush," and had been addressed by him face to face, and yet so awful were the scenes at Horeb that even he could not bear it with composure. What may we then suppose to have been the alarm of the body of the people, when the mind of the great leader himself was thus overpowered!

And so terrible was the (i) sight, [that] Moses said, I exceedingly fear and quake:)
(i) The shape and form which he saw, which was no counterfeit and forged shape, but a true one.

And so terrible was the sight,.... Of the smoke, fire, and lightnings; or of God himself, who descended on the mount; with which agrees the Arabic version, which renders the words, "and so terrible was he who vouchsafed himself to be seen"; not in the bush burning with fire; at which time Moses was afraid to look upon God, Exodus 3:6 but on Mount Sinai, when the law was given:
that Moses said, I exceedingly fear and quake: perhaps he might say this, when he spake, and God answered him, Exodus 19:19. These words are nowhere recorded in Scripture; wherefore the apostle had them either by divine revelation, or from tradition, confirmed by the former: for the Jews have a notion that Moses did quake and tremble, and when upon the mount; and that he expressed his fear and dread. They have such a tradition as this (e);
"when Moses ascended on high, the ministering angels said before the holy blessed God, Lord of the world, what has this man, born of a woman, to do among us? he said unto them, to receive the law he is come; they replied before him, that desirable treasure, which is treasured up with thee, nine hundred, and seventy, and four generations, before the world was created, dost thou seek to give to flesh and blood? "What is man, that thou art mindful of him, and the son of man, that thou visitest him? who hast set thy glory above the heavens!" The holy blessed God said to Moses, return them an answer; he said, before him, Lord of the world, , "I am afraid", lest they should burn, (or consume) me, with the breath of their mouth.''
Compare this last clause with 2-Thessalonians 2:8 and elsewhere (f) those words being cited, he called unto Moses, Exodus 25:16 it is observed:
"this Scripture comes not, but "to terrify him"; that so the law might be given with fear, fervour, and trembling; as it is said, Psalm 2:11''
Once more (g),
"at the time that the holy blessed God said to Moses, "go, get thee down, for thy people have corrupted themselves", Exodus 32:7 , "Moses trembled"; and he could not speak, &c.''
And again, it is said (h), that when Moses was on Mount Sinai, supplicating for the people of Israel, five destroying angels appeared, and immediately , "Moses was afraid". Now this circumstance is mentioned by the apostle, to aggravate the terror of that dispensation; that Moses, a great and good man; and who had much familiarity with God; the general of the people of Israel; their leader and commander; a man of great courage and presence of mind; and was their mediator between God and them; and yet feared, and quaked: the best of men are not without sin; and the most holy man on earth cannot stand before a holy God, and his holy law, upon the foot of his own righteousness, without trembling: it is an awful thing to draw nigh to God; and there is no such thing as doing it without a Mediator; and that Mediator must be more than a creature: and it is our happiness that we have such a Mediator, who never feared, nor quaked; who failed not, nor was he discouraged.
(e) T. Bab. Sabbat, fol. 88. 2. Yalkut, 2. par. 2. fol. 92. (f) T. Bab. Yoma, fol. 4. 2. (g) Zohar in Exod. fol. 84. 4. (h) Midrash Kohelet, fol. 69. 4.

the sight--the vision of God's majesty.
quake--Greek, "I am in trembling"; "fear" affected his mind: "trembling," his body. Moses is not recorded in Exodus to have used these words. But Paul, by inspiration, supplies (compare Acts 20:35; 2-Timothy 3:8) this detail. We read in Deuteronomy 9:19, Septuagint, of similar words used by Moses after breaking the two tables, through fear of God's anger at the people's sin in making the golden calves. He doubtless similarly "feared" in hearing the ten commandments spoken by the voice of Jehovah.

Even Moses - Though admitted to so near an intercourse with God, who "spake to him as a man speaketh to his friend." At other times he acted as a mediator between God and the people. But while the ten words were pronounced, he stood as one of the hearers, Exodus 19:25; Exodus 20:19.