Shmini Atzeret:

The Eighth Day of Assembly is separate from Sukkot, but still connected.  It is if HaShem is saying to the children of Israel, "Let's stay together just one more day…don't go yet."  This Festival is considered a Shabbat.  Scholarship within the Messianic Jewish Movement and within Biblical Christianity has determined that Yeshua would have born the first day of Sukkot and then circumcised the Eighth Day - Shmini Atzeret.  Therefore, this Holy Day is linked with history, agriculture, and the miracle-workings of G-d.  Leviticus 23:36; Luke 2:21-28.