Clever collateral incarceration[1]
…ויקח מאתם את-שמעון ויאסר אתו לעיניהם
…[Yosef] took Shimon from them and imprisoned him in front of their eyes[2]
Yosef, disguised as the viceroy of Egypt, demanded from his brothers that they bring their remaining brother Binyamin to Egypt. Yosef wanted to see if they would abandon Binyamin just as they abandoned him[3]. The brothers, knowing their father Yaakov would never let Binyamin out of his sight, pleaded with the viceroy to spare their brother. As collateral to ensure their compliance, Yosef imprisoned Shimon, and set the others free to fetch Binyamin.