And when the cloud was taken up from over the tabernacle, the children of Israel went onward in all their journeys:

King James Translators' Notes

went onward: Heb. journeyed

Jamieson-Fausset-Brown Bible Commentary

36. when the cloud was taken up from over the tabernacle-In journeying through the sandy, trackless deserts of the East, the use of torches, exhibiting a cloud of smoke by day and of fire by night, has been resorted to from time immemorial. The armies of Darius and Alexander were conducted on their marches in this manner [Faber]. The Arab caravans in the present day observe the same custom; and materials for these torches are stored up among other necessary preparations for a journey. Live fuel, hoisted in chafing dishes at the end of long poles, and being seen at a great distance, serves, by the smoke in the daytime and the light at night, as a better signal for march than the sound of a trumpet, which is not heard at the extremities of a large camp [Laborde]. This usage, and the miracle related by Moses, mutually illustrate each other. The usage leads us to think that the miracle was necessary, and worthy of God to perform; and, on the other hand, the miracle of the cloudy pillar, affording double benefit of shade by day and light at night, implies not only that the usage was not unknown to the Hebrews, but supplied all the wants which they felt in common with other travellers through those dreary regions [Faber, Hess, Grandpierre]. But its peculiar appearance, unvarying character, and regular movements, distinguished it from all the common atmospheric phenomena. It was an invaluable boon to the Israelites, and being recognized by all classes among that people as the symbol of the Divine Presence, it guided their journeys and regulated their encampments (compare Ps 29:1-11; 105:1-45).

Matthew Henry's Concise Commentary

40:34-38 The cloud covered the tabernacle even in the clearest day; it was not a cloud which the sun scatters. This cloud was a token of God's presence to be seen day and night, by all Israel, that they might never again question, Is the Lord among us, or is he not? It guided the camp of Israel through the wilderness. While the cloud rested on the tabernacle, they rested; when it removed, they followed it. The glory of the Lord filled the tabernacle. In light and fire the Shechinah made itself visible: God is Light; our God is a consuming Fire. Yet so dazzling was the light, and so dreadful the fire, that Moses was not able to enter into the tent of the congregation, till the splendour was abated. But what Moses could not do, our Lord Jesus has done, whom God caused to draw near; and who has invited us to come boldly, even to the mercy-seat. Being taught by the Holy Spirit to follow the example of Christ, as well as to depend upon him, to attend his ordinances, and obey his precepts, we shall be kept from losing our way, and be led in the midst of the paths of judgment, till we come to heaven, the habitation of his holiness. BLESSED BE GOD FOR JESUS CHRIST!