Albert Barnes Commentary Exodus 33:2-3

"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: unto a land flowing with milk and honey: for I will not go up in the midst of thee, for thou art a stiffnecked people, lest I consume thee in the way." — Exodus 33:2-3 (ASV)

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).