See Exodus 3:8.

For I will not go up in the midst of thee - The covenant on which the original promise Exodus 23:20-23 was based had been broken by the people. Yahweh now therefore declared that though His Angel should go before Moses, He would withhold His own favoring presence. The nation should be put on a level with other nations, to lose its character as the people in special covenant with Yahweh (see the note at Exodus 33:16). Thus were the people forcibly warned that His presence could prove a blessing to them only on condition of their keeping their part of the covenant Exodus 33:3. If they failed in this, His presence would be to them "a consuming fire" (Deuteronomy 4:24; compare Exodus 32:10).

I will send an angel - In Exodus 23:20, God promises to send an angel to conduct them into the good land, in whom the name of God should be; that is, in whom God should dwell. See Clarke's note on Exodus 23:20 (note). Here he promises that an angel shall be their conductor; but as there is nothing particularly specified of him, it has been thought that an ordinary angel is intended, and not that Angel of the Covenant promised before. And this sentiment seems to be confirmed by the following verse.

And I will send an angel before thee,.... Not the angel before promised, Exodus 23:20 the Angel of his presence, the eternal Word and Son of God, but a created angel; and so Aben Ezra observes, he does not say the Angel that was known, that his name was in him; though even this was to be looked upon as a favour, and showed that he had not utterly cast them off:

and I will drive out the Canaanite, the Amorite, and the Hittite, the Perizzite, the Hivite, and the Jebusite; who were now the inhabitants of the land, and these he promises drive out, to make way for their possession of it; and that "by his hand", as the Targum of Jonathan interprets it, by the hand of the angel. Only six nations are mentioned, though there were seven; the Girgashite is omitted, but added in the Septuagint version.

And I will send an angel before thee; and I will drive out the Canaanite, the Amorite, and the Hittite, and the Perizzite, the Hivite, and the Jebusite:

Margin angel

See Scofield Note: "Heb 1:4".

33:1-6 Those whom God pardons, must be made to know what their sin deserved. Let them go forward as they are; this was very expressive of God's displeasure. Though he promises to make good his covenant with Abraham, in giving them Canaan, yet he denies them the tokens of his presence they had been blessed with. The people mourned for their sin. Of all the bitter fruits and consequences of sin, true penitents most lament, and dread most, God's departure from them. Canaan itself would be no pleasant land without the Lord's presence. Those who parted with ornaments to maintain sin, could do no less than lay aside ornaments, in token of sorrow and shame for it.