Adam Clarke on Genesis 42:6

Joseph was the governor - שליט shallit, an intendant, a protector, from שלט skalat, to be over as a protector; hence שלטים shelatim, shields, or arms for protection and defense, 2Sam 8:7; and שלטון shilton, power and authority, Ecc 8:4, Ecc 8:8; and hence the Arabic sultan, a lord, prince, or king, from salata, he obtained and exercised dominion, he ruled. Was it not from this very circumstance, Joseph being shallit, that all the Mohammedan governors of Egypt, etc., took the title of sultan? Bowed down themselves before him - Thus fulfilling the prophetic dream, Gen 37:7, Gen 37:8, which they had taken every precaution to render null and void. But there is neither might nor counsel against the Lord.