Leviticus 23:33-35

³³And the Lord spoke to Moses, saying:

³⁴Say to the children of Israel: From the fifteenth day of this same seventh month, shall be kept the feast of tabernacles seven days to the Lord.

³⁵The first day shall be called most solemn and most holy: you shall do no servile work therein. And seven days you shall offer holocausts to the Lord.