And the LORD went before them by day in a pillar of a {l} cloud, to lead them the way; and by night in a pillar of fire, to give them light; to go by day and night:

(l) To defend them from the heat of the sun.

Wesley's Notes

13:21 And the Lord went before them in a pillar - In the two first stages, it was enough that God directed Moses whither to march; he knew the country, and the road; but now they are come to the edge of the wilderness, they would have occasion for a guide, and a very good guide they had, infinitely wise, kind, and faithful, the Lord went up before them; The Shechinah or appearance of the divine Majesty, which was a precious manifestation of the eternal Word, who in the fulness of time was to be made flesh, and dwell among us. Christ was with the church in the wilderness, 1Cor 10:9. What a satisfaction to Moses and the pious Israelites, to be sure that they were under a divine conduct? They need not fear missing their way who were thus led, nor being lost who were thus directed; they need not fear being benighted, who were thus illuminated, nor being robbed, who were thus protected. And they who make the glory of God their end, and the word of God their rule, the spirit of God the guide of their affections, and the providence of God the guide of their affairs, may be confident that the Lord goes before them, as truly is he went before Israel in the wilderness, though not so sensibly. They had sensible effects of God's going before them in this pillar. For, It led them the way in that vast howling wilderness, in which there was no road, no track, no way - marks through which they had no guides. When they marched, this pillar went before them, at the rate that they could follow, and appointed the place of their encampment, as infinite Wisdom saw fit; which eased them from care, and secured them from danger, both in moving, and in resting. It sheltered them from the heat by day, which at sometimes of the year was extreme: And it gave them light by night when they had occasion for it.

Jamieson-Fausset-Brown Bible Commentary

21, 22. the Lord went before them-by a visible token of His presence, the Shekinah, in a majestic cloud (Ps 78:14; Ne 9:12; 1Co 10:1), called "the angel of God" (Ex 14:19; 23:20-23; Ps 99:6, 7; Isa 63:8, 9).

Matthew Henry's Concise Commentary

13:21,22 The Lord went before them in a pillar, or appearance of the Divine Majesty. Christ was with the church in the wilderness, 1Co 10:9. Those whom God brings into a wilderness, he will not leave nor lose there, but will take care to lead them through it. It was great satisfaction to Moses and the pious Israelites, to be sure that they were under Divine guidance. Those who make the glory of God their end, and the word of God their rule, the Spirit of God the guide of their affections, and the providence of God the guide of their affairs, may be sure that the Lord goes before them, though they cannot see it with their eyes: we must now live by faith. When Israel marched, this pillar went before, and pointed out the place of encampment, as Divine Wisdom saw fit. It sheltered by day from the heat, and gave light by night. The Bible is a light to our feet, a lantern to our paths, with which the Saviour's love has provided us. It testifies of Christ. It is to us like the pillar to the Israelites. Listen to that voice which cries, I am the Light of the world; he that followeth me shall not walk in darkness, but shall have the Light of life, Joh 8:12. Jesus Christ alone, as shown in the Bible, and as the Holy Spirit, in answer to prayer, recommends him to the soul, is the Way, the Truth, and the Life, Joh 14:6.