Commentaries:
God's sovereignty and involvement with the details of Joseph in Egypt persist from beginning to end; everything happens when, where, and how God planned. Undoubtedly, God is already working in and through Joseph as a lad of 17. But between 17 and 30, Joseph's life is a veritable roller coaster ride from top to bottom and from bottom to top.
The story shows his faith in God; through it all he trusts Him, not fully understanding every detail until after it is over. But God works throughout those years and in all the details toward a purpose and a time He had determined in advance. The same is true regarding Abraham and Sarah's 25-year wait for Isaac.
John W. Ritenbaugh
The Sovereignty of God: Part Four