Vayikra (Leviticus) 23:33-36
33 Then Yahweh spoke to Moshe, saying,
34 “Speak to the children of Israel, saying: ‘The fifteenth day of this seventh month shall be the Feast of Tabernacles for seven days to Yahweh.
35 On the first day there shall be a set-apart convocation. You shall do no customary work on it.
36 For seven days you shall offer an offering made by fire to Yahweh. On the eighth day you shall have a set-apart convocation, and you shall offer an offering made by fire to Yahweh. It is a set-apart assembly, and you shall do no customary work on it.
Sukkot is a 7-day feast, followed by the Eighth Day Assembly (Shemini Atzeret). It is a time of rehearsal for when we will again dwell in tabernacles with Yahweh (Hosea 12:9), and after Armageddon (Zechariah 14:16-18), and also when He will be our Tabernacle in the New Jerusalem (Revelation 21:3).