Levítico 23:34

The fifteenth day of this seventh month. — That is, the month Tishri, corresponding to the end of September and the beginning of October, and only four days after the day of Atonement.

Shall be the feast of tabernacles. — How and where these tabernacles are to be erected the law here gives no directions. The details, as in many other enactments, are left to the administrators of the Law. From the account of the first celebration of this festival after the return from Babylon, the Jews, according to the command of Ezra, made themselves booths upon the roofs of houses, in the courts of their dwellings, and of their sanctuary, in the streets of the Water-gate and the gate of Ephraim. These tabernacles they made of olive branches, pine branches, myrtle branches, palm branches, and branches of thick trees (Neemias 8:15). The construction of these temporary abodes, however, was more minutely defined by Ezra’s successors. It was ordained during the second Temple that the interior of each tabernacle must not be higher than twenty cubits, and not lower than ten palms, it must at least have three walls, with a thatched roof partially open so as to admit a view of the sky and the stars. It must not be under a tree, nor must it be covered with a cloth, or with any material which contracts defilement. Only branches or shrubs which grow out of the ground are to be used for the covering. These booths the Israelites began to erect on the morrow after the Day of Atonement. On the fourteenth, which was the day of preparation, the pilgrims came up to Jerusalem, and on the eve of this day the priests proclaimed the approach of the holy convocation by the blasts of trumpets. As on the feasts of Passover and Pentecost, the altar of burnt-offering was cleansed in the first night watch, and the gates of the Temple, as well as those of the inner court, were opened immediately after midnight, for the convenience of the priests who resided in the city, and for the people, who filled the court before the cock crew, to have their sacrifices duly examined by the priests.