 According to Rav Avira, at the Birkat HaMazon (Grace after Meals) following this feast, the Cup of Blessing will be passed from Abraham to Isaac to Jacob to Moses to Joshua, each of whom will cite some sin or imperfection and claim unworthiness to lead the blessing.The cup will then pass to King David, who will take it and lead the Birkat HaMazon.The Rabbis cite the verse "I shall raise the cup of salvation, and call upon the name of the Lord" (Psalms 16