וּבְיוֹם֙ הָקִ֣ים אֶת־הַמִּשְׁכָּ֔ן כִּסָּ֤ה הֶֽעָנָן֙ אֶת־הַמִּשְׁכָּ֔ן לְאֹ֖הֶל הָעֵדֻ֑ת וּבָעֶ֜רֶב יִהְיֶ֧ה עַֽל־הַמִּשְׁכָּ֛ן כְּמַרְאֵה־אֵ֖שׁ עַד־בֹּֽקֶר׃
And on the day that the tabernacle was reared up the cloud covered the tabernacle, even the tent of the testimony; and at even there was upon the tabernacle as it were the appearance of fire, until morning.
Read kabbalistic (mystical) interpretation of Numbers 9:15: and classical mystical sources.