Final answer:
Joseph conceals a silver cup in his brothers' sack after they leave the banquet feast in Egypt with Benjamin. This act is a prelude to him eventually revealing his true identity to them.
Step-by-step explanation:
After the banquet feast, when Joseph's brothers are leaving Egypt with Benjamin, Joseph conceals a silver cup in their sack. This action is the beginning of a sequence of events that eventually leads to Joseph revealing his true identity to his brothers, who are unaware that the powerful Egyptian official they are dealing with is, in fact, their brother whom they sold into slavery years before. Joseph's maneuver with the silver cup is a test of his brothers' character and loyalty, especially towards their youngest brother, Benjamin.