|לו וּבְהֵעָלוֹת הֶעָנָן מֵעַל הַמִּשְׁכָּן יִסְעוּ בְּנֵי יִשְׂרָאֵל בְּכֹל מַסְעֵיהֶם.||36 And whenever the cloud was taken up from over the tabernacle, the children of Israel went onward, throughout all their journeys.|
|לז וְאִם לֹא יֵעָלֶה הֶעָנָן וְלֹא יִסְעוּ עַד-יוֹם הֵעָלֹתוֹ.||37 But if the cloud was not taken up, then they journeyed not till the day that it was taken up.|
|לח כִּי עֲנַן ה’ עַל הַמִּשְׁכָּן יוֹמָם וְאֵשׁ תִּהְיֶה לַיְלָה בּוֹ לְעֵינֵי כָל בֵּית יִשְׂרָאֵל בְּכָל מַסְעֵיהֶם.||38 For the cloud of the LORD was upon the tabernacle by day, and there was fire therein by night, in the sight of all the house of Israel, throughout all their journeys.|
He learns this from 2 places: (1) the Torah tells us in passuk 36 that the cloud would only rise when it was time for Bnei Yisrael to travel to their next destination. If the cloud were replaced by the fire every night, then it would have to move from its spot, and it only did so when it was time to embark to the next location. Bnei Yisrael, however, didn’t travel every night! Thus, it must be that the cloud stayed in place every night and became a large fiery pillar. (2) Additionally, he quotes from later in the Torah, in Bamidbar 9:15-16, which describes how the Annan and Amud/Mar’eh Aish functioned:
|טו וּבְיוֹם, הָקִים אֶת-הַמִּשְׁכָּן, כִּסָּה הֶעָנָן אֶת-הַמִּשְׁכָּן, לְאֹהֶל הָעֵדֻת; וּבָעֶרֶב יִהְיֶה עַל-הַמִּשְׁכָּן, כְּמַרְאֵה-אֵשׁ–עַד-בֹּקֶר.||15 And on the day that the tabernacle was reared up the cloud covered the tabernacle, even the tent of the testimony; and at evening there was upon the tabernacle as it were the appearance of fire, until morning.|
|טז כֵּן יִהְיֶה תָמִיד, הֶעָנָן יְכַסֶּנּוּ; וּמַרְאֵה-אֵש לָיְלָה.||16 So it was always: the cloud covered it, and the appearance of fire by night.|
|יז וּלְפִי הֵעָלוֹת הֶעָנָן, מֵעַל הָאֹהֶל–וְאַחֲרֵי כֵן, יִסְעוּ בְּנֵי יִשְׂרָאֵל; וּבִמְקוֹם, אֲשֶׁר יִשְׁכָּן-שָׁם הֶעָנָן–שָׁם יַחֲנוּ, בְּנֵי יִשְׂרָאֵל.||17 And whenever the cloud was taken up from over the Tent, then after that the children of Israel journeyed; and in the place where the cloud abode, there the children of Israel encamped.|
The Netziv doesn’t say this explicitly, (so this could be entirely incorrect) but I believe that there is an underlying message being conveyed here. The protective cloud and the intense flame were not just from the same source (Hashem – the source of everything), but it was exactly the same “object”. At times the Mishhkan was covered by a cloud and other times by fire. The Midrash in Pekudei notes that Bnei Yisrael rejoiced when they saw the cloud and were in fear of the consuming flame in the evening. At times we feel Hashem’s love and benevolence; and then there are times, lo aleinu, when we feel scared, confused and engulfed by flames. It is the same Hashem who controls both.
The last 2 words of the Sefer, tell us that this Annan / Aish was with Bnei Yisrael “bCHOL mah’seihem” = in ALL their journeys. The Netziv points out from the Torah’s use of KOL that Hashem was with them not just for the travels initiated by Hashem, but through all their travels and sojourns; through the positive journeys and encampments and the negative ones, Hashem was with them. Says the Netziv, at every stop the purpose of the Annan / Aish was fully intact and “tamid”.
The night can be dark and frightening, but, b’ezras Hashem, we can maintain emunah at night and find comfort in the morning.