(Sukkot - Tabernacles ( or Booths ) is found in Deuteronomy 16 starting at v13, Celebrate the Feast of Tabernacles for seven days after you have gathered the produce of your threshing floor and your winepress. Be joyful at your Feast--you, your sons and daughters, your menservants and maidservants, and the Levites, the aliens, the fatherless and the widows who live in your towns. For seven days celebrate the Feast to the LORD your God at the place the LORD will choose. For the LORD your God will bless you in all your harvest and in all the work of your hands, and your joy will be complete.
Also, Leviticus 23 v39-43 says, " `So beginning with the fifteenth day of the seventh month, after you have gathered the crops of the land, celebrate the festival to the LORD for seven days; the first day is a day of rest, and the eighth day also is a day of rest. On the first day you are to take choice fruit from the trees, and palm fronds, leafy branches and poplars, and rejoice before the LORD your God for seven days. Celebrate this as a festival to the LORD for seven days each year. This is to be a lasting ordinance for the generations to come; celebrate it in the seventh month. Live in booths for seven days: All native-born Israelites are to live in booths so your descendants will know that I had the Israelites live in booths when I brought them out of Egypt. I am the LORD your God.' "
( Sukkot is the plural form of Sukkah - adding "ot" in Hebrew is equivalent to adding an "s" in English )
(Sukkot is pronounced as "sue coat" - emphasis on the second syllable )
Sukkot is the seventh of the seven feasts in Torah (the five books of Teaching (Law) ) ( Remember seven is for completeness) Tabernacles is the only feast with specific instructions to Rejoice.
(Tabernacles is reckoned by scholars to be the time of Yeshua's birth. )
http://fp.thebeers.f9.co.uk/christian_dates.htm