Thou goest with us - It was this which alone distinguished (rather than "separated") them from other nations, and which alone would render the land of promise a home to be desired. Compare 2 Samuel 7:23.

So shall we be separated - By having this Divine protection we shall be saved from idolatry, and be preserved in thy truth and in the true worshipping of thee; and thus shall we be separated from all the people that are upon the face of the earth: as all the nations of the world, the Jews only excepted, were at this time idolaters.

For wherein shall it be known here,.... At Sinai, among the mountains in the wilderness:

that I and thy people have found grace in thy sight: were acceptable to him, highly esteemed by him, and had received peculiar favours from him; what evidence would there be of this? how would it appear to others? what knowledge could they have of it?

is it not in that thou goest with us? in such a grand majestic manner, and so visible as in a pillar of cloud by day, and a pillar of fire by night: this is a full proof, and a strong and convincing argument, even to a demonstration, that they were a special and peculiar people, the favourites of God, highly esteemed and honoured by him; but should this be discontinued, as seemed to be threatened, there would be nothing to demonstrate that they had found more grace and favour than other people; but this being the case:

so shall we be separated, I and thy people, from all the people that are upon the face of the earth; distinguished by this favour from them, and that in a very wonderful and marvellous manner, as the word signifies; and so some render it, "marvellously separated" (a); for the pillar of cloud and fire was a very marvellous thing, and distinguished the people of Israel from all others in a surprising manner, none having been ever favoured in the like manner.

(a) "marvellously separated", Ainsworth.

For wherein shall it be known here that I and thy people have found grace in thy sight? is it not in that thou goest with us? so shall we be separated, I and thy people, from all the people that are upon the face of the earth.

33:16 Wherein shall it be known to the nations that have their eyes upon us, that I, and thy people, have found grace in thy sight; so as to be separated from all people upon earth? Is it not that thou goest with us? Nothing short of that can answer these characters.

33:12-23 Moses is very earnest with God. Thus, by the intercession of Christ, we are not only saved from ruin, but become entitled to everlasting happiness. Observe here how he pleads. We find grace in God's sight, if we find grace in our hearts to guide and quicken us in the way of our duty. Moses speaks as one who dreaded the thought of going forward without the Lord's presence. God's gracious promises, and mercy towards us, should not only encourage our faith, but also excite our fervency in prayer. Observe how he speeds. See, in a type, Christ's intercession, which he ever lives to make for all that come to God by him; and that it is not by any thing in those for whom he intercedes. Moses then entreats a sight of God's glory, and is heard in that also. A full discovery of the glory of God, would overwhelm even Moses himself. Man is mean, and unworthy of it; weak, and could not bear it; guilty, and could not but dread it. The merciful display which is made in Christ Jesus, alone can be borne by us. The Lord granted that which would abundantly satisfy.
God's goodness is his glory; and he will have us to know him by the glory of his mercy, more than by the glory of his majesty. Upon the rock there was a fit place for Moses to view the goodness and glory of God. The rock in Horeb was typical of Christ the Rock; the Rock of refuge, salvation, and strength. Happy are they who stand upon this Rock. The cleft may be an emblem of Christ, as smitten, crucified, wounded, and slain. What follows, denotes the imperfect knowledge of God in the present state, even as revealed in Christ; for this, when compared with the heavenly sight of him. is but like seeing a man that is gone by, whose back only is to be seen. God in Christ, as he is, even the fullest and brightest displays of his glory, grace, and goodness, are reserved to another state.