Leviticus 23:34
33 The Lord spoke to Moses: 34 “Tell the Israelites, ‘On the fifteenth day of this seventh month is the Feast of Shelters for seven days to the Lord. 35 On the first day is a holy assembly; you must do no regular work. 36 For seven days you must present a gift to the Lord. On the eighth day there is to be a holy assembly for you, and you must present a gift to the Lord. It is a solemn assembly day; you must not do any regular work.
Jubilees 16:21
19 Then we went on our way and told Sarah all that we had reported to him. The two of them were extremely happy. 20 There he built an altar for the Lord who had recued him and who was making him so happy in the country where he resided as an alien. He celebrated a joyful festival in this month — for seven days — near the altar which he had built at the well of the oath. 21 He constructed tents for himself and his servants during this festival. He was the first to celebrate the festival of tabernacles on the earth. 22 During these seven days he was making — throughout all the days, each and every day — an offering to the Lord on the altar: two bulls, two rams, seven sheep, one goat for sins in order to atone through it for himself and his descendants.
Notes and References
"... the author was so bold as to assert that the very reason for the existence of these holy days was to be found not in the divinely-given prescriptions of the Sinai covenant, but in the events of the patriarchs’ own lives. That is to say, God did not command Abraham to celebrate the Festival of Booths (Sukkot); on the contrary, such-and-such a thing happened in Abraham’s life, and as a result he inaugurated the celebration of this festival on his own initiative (Jubilees 16:5-27). Only later did God tell Moses to promulgate a law in the Torah (Leviticus 23:33-35) commanding Israelites to celebrate the festival that Abraham had initiated, and to celebrate it on the precise date that Abraham had chosen for it ..."
Kugel, James L. A Walk through Jubilees: Studies in the Book of Jubilees and the World of Its Creation (p. 8) Brill, 2012