exodus 40:34 Then a cloud covered the tent of the congregation, and the glory of the LORD filled the tabernacle. - Free Bible Online

      34. a cloud--literally, "The cloud," the mystic cloud which was the well-known symbol of the Divine Presence. After remaining at a great distance from them on the summit of the mount, it appeared to be in motion; and if many among them had a secret misgiving about the issue, how the fainting heart would revive, the interest of the moment intensely increase, and the tide of joy swell in every bosom, when that symbolic cloud was seen slowly and majestically descending towards the plain below and covering the tabernacle. The entire and universal concealment of the tabernacle within the folds of an impervious cloud was not without a deep and instructive meaning; it was a protection to the sacred edifice from the burning heats of the Arabian climate; it was a token of the Divine Presence; and it was also an emblem of the Mosaic dispensation, which, though it was a revelation from heaven, yet left many things hid in obscurity; for it was a dark cloud compared with the bright cloud, which betokened the clearer and fuller discoveries of the divine character and glory in the gospel (Mt 17:5).
      the glory of the Lord filled the tabernacle--that is, light and fire, a created splendor, which was the peculiar symbol of God (1Jo 1:5). Whether this light was inherent in the cloud or not, it emanated from it on this occasion, and making its entry, not with the speed of a lightning flash as if it were merely an electric spark, but in majestic splendor, it passed through the outer porch into the interior of the most holy place (1Ki 8:10; Joh 1:14). Its miraculous character is shown by the fact, that, though "it filled the tabernacle," not a curtain or any article of furniture was so much as singed.

JFB.