The Ushpizin are the seven mystical visitors whom we welcome to our succot throughout the holiday, They are Abraham, Isaac, Jacob, Joseph, Moses, Aaron and David. Abraham visits on the first night, Isaac on the second, and so on.
Ushpizin comes from the Aramaic word, ushpiz, meaning a guest and also a lodging place or an inn. In modern Hebrew, the related word ishpuz means hospitalisation.
Apparently, the earliest source for the custom of welcoming the Ushpizin on Succot is in the Zohar, the classic of Kabbalah. The Zohar makes clear that a central reason is to stress the importance of inviting guests to share the holiday with us: "One must also gladden the poor, and the portion [that would otherwise have been set aside for these Ushpizin guests] should go to the poor. For if a person sits in the shadow of faith and invites those guests and does not give their portion [to the poor], they all remain distant from him" (Zohar III 103b).
Ushpizin, one of the best recent Israeli films, follows the spirit of the Zohar. Moshe and Mali are a childless couple whose forbearance is sorely tried when two disreputable ex-con friends of Moshe's move in with them for the holiday. The hardest test of faith is when one of them eats the hosts' 1000-shekel etrog. The couple's heroic patience and hospitality is rewarded with a child.