The Ramban interprets the descent of the Divine Presence into the Mishkan as a fulfillment of God's promise to dwell among Israel, underscoring its significance as a spiritual beacon.
וּכְבוֹד ה' מָלֵא אֶת הַמִּשְׁכָּן, כִּי תּוֹכוֹ מָלֵא הַכָּבוֹד, כִּי הַכָּבוֹד שׁוֹכֵן בְּתוֹךְ הֶעָנָן תּוֹךְ הַמִּשְׁכָּן, כְּעִנְיָן שֶׁנֶּאֱמַר בְּהַר סִינַי (שמות כ':כ"א) "אֶל הָעֲרָפֶל אֲשֶׁר שָׁם הָאֱלֹהִים", וְאָמַר כִּי לֹא יָכוֹל מֹשֶׁה לָבֹא אֶל אֹהֶל מוֹעֵד (שמות מ':ל"ה) אֲפִלּוּ אֶל הַפֶּתַח, מִפְּנֵי שֶׁהָיָה הֶעָנָן מְכַסֶּה אוֹתוֹ וְלֹא הָיָה רַשַּׁאי לָבֹא בְּתוֹךְ הֶעָנָן. וְעוֹד, כִּי הַמִּשְׁכָּן מָלֵא כְּבוֹד ה' וְאֵיךְ יִכָּנֵס בּוֹ. וְהַטַּעַם, שֶׁלֹּא יָבֹא שָׁם בְּלֹא רְשׁוּת, אֲבָל יִקְרָא אוֹתוֹ וְיָבֹא בְּתוֹךְ הֶעָנָן כַּאֲשֶׁר עָשָׂה בְּהַר סִינַי "וַיִּקְרָא אֶל מֹשֶׁה בַּיּוֹם הַשְּׁבִיעִי מִתּוֹךְ הֶעָנָן" (שמות כ"ד:ט"ז), וְאָמַר "וַיָּבֹא מֹשֶׁה בְּתוֹךְ הֶעָנָן" (שם יח). וְעַל דֶּרֶךְ הַפְּשָׁט, בַּעֲבוּר שֶׁנֶּאֱמַר "וַיְדַבֵּר ה' אֵלָיו מֵאֹהֶל מוֹעֵד" (ויקרא א א) לֹא נִכְנַס מֹשֶׁה לַמִּשְׁכָּן, אֲבָל קָרָא אוֹתוֹ מֵאֹהֶל מוֹעֵד וְעָמַד פֶּתַח אֹהֶל מוֹעֵד וַיְדַבֵּר אֵלָיו: וְרַבּוֹתֵינוּ אָמְרוּ (ת"כ פתיחתא ח) כָּתוּב אֶחָד אוֹמֵר "וְלֹא יָכֹל מֹשֶׁה לָבוֹא אֶל אֹהֶל מוֹעֵד", וְכָתוּב אַחֵר אוֹמֵר "וּבְבֹא מֹשֶׁה אֶל אֹהֶל מוֹעֵד" (במדבר ז פט), הִכְרִיעַ "כִּי שָׁכַן עָלָיו הֶעָנָן". כִּי לְדַעְתָּם "וּבְבֹא מֹשֶׁה אֶל אֹהֶל מוֹעֵד", שֶׁיָּבֹא שָׁם בְּלֹא קְרִיאָה מִדַּעְתּוֹ, אוֹ מִפְּנֵי שֶׁאָמַר שָׁם "וַיִּשְׁמַע אֶת הַקּוֹל מִדַּבֵּר אֵלָיו מֵעַל הַכַּפֹּרֶת" נִרְאָה לָהֶם שֶׁהָיָה מֹשֶׁה עוֹמֵד בְּתוֹךְ הָאֹהֶל לִפְנֵי הַכַּפֹּרֶת, וְכָל עֵת הֱיוֹת כְּבוֹד הַשֵּׁם מָלֵא אֶת הַמִּשְׁכָּן לֹא נִכְנַס מֹשֶׁה בְּתוֹכוֹ, וּלְכָךְ יֹאמְרוּ שֶׁהָיָה זֶה לְאַחַר שֶׁנִּסְתַּלֵּק הֶעָנָן, כְּלוֹמַר שֶׁנִּסְתַּלֵּק מִלְּכַסּוֹת כָּל הָאֹהֶל וְאֵין הַכָּבוֹד מָלֵא אֶת הַמִּשְׁכָּן, כִּי לֹא הָיָה זֶה רַק בַּיּוֹם הַשְּׁמִינִי בְּרֶדֶת שָׁם הַכָּבוֹד. וְהַקְּרִיאָה שֶׁאָמַר "וַיִּקְרָא אֶל מֹשֶׁה וַיְדַבֵּר ה' אֵלָיו מֵאֹהֶל מוֹעֵד" (ויקרא א א), עַל דַּעְתָּם קֹדֶם לָכֵן הָיְתָה, כַּאֲשֶׁר פֵּרַשְׁתִּי לְמַעְלָה (רמב"ן על שמות מ':ב'). וְיִתָּכֵן שֶׁהַכָּתוּב שֶׁיֹּאמַר פַּעַם אַחֶרֶת וּכְבוֹד ה' מָלֵא אֶת הַמִּשְׁכָּן יִרְמֹז אֶל הַכָּבוֹד הַשּׁוֹכֵן בְּקִרְבּוֹ:
AND THE GLORY OF THE ETERNAL FILLED THE TABERNACLE, this means that it was filled completely with the Glory, for the Glory rested within the cloud inside the Tabernacle, just as it is said with reference to Mount Sinai, unto the thick darkness where G-d was. It states further on that Moses was not able to come into the Tent of Meeting — even to the door, because the cloud covered it, and he was not permitted to come into the cloud. Moreover, the Glory of the Eternal filled the Tabernacle, so how could he enter it? The reason for this was so that Moses should not go in without permission, but instead G-d would call him and then he was to come into the midst of the cloud, just as He had done at Mount Sinai, as it is said, and He called unto Moses on the seventh day out of the midst of the cloud, and then it says, And Moses entered into the midst of the cloud. In line with the plain meaning of Scripture, it is because it is said, and the Eternal spoke unto him out of the Tent of Meeting that Moses did not enter the Tabernacle, but G-d called him from the Tent of Meeting and he stood at its door and He spoke to him. But our Rabbis have said: “One verse states, And Moses was not able to enter into the Tent of Meeting, and another verse states, and when Moses went into the Tent of Meeting [thus the two verses appear to be contradictory]! The matter is decided by the passage, because the cloud abode thereon.” For in the opinion of the Rabbis, the phrase and when Moses went into the Tent of Meeting, means that he went inside of his own accord without being called. Or it may be that because Scripture states there, and he heard the Voice speaking unto him from above the ark-cover, therefore it appeared to the Rabbis that Moses stood within the Tent before the ark-cover. Now as long as the Glory of G-d filled the Tabernacle, Moses did not enter it. Therefore they say that he only would enter after the cloud withdrew, meaning after it withdrew from covering the whole Tent, and the Glory no longer filled the Tabernacle. That was only on the eighth day of the installation when the Glory descended there, and as for the call that came to Moses, of which it is said, And he called unto Moses, that happened, in the opinion of the Rabbis, before [the eighth day, namely, on the first day of the installation], as I have explained above. It is possible that the verse before us which repeats, and the Glory of the Eternal filled the Tabernacle [when it had already stated, and the cloud covered the Tent of Meeting], alludes to the Glory that dwells within it.