(Thus did We give full authority to Yusuf in the land), in Egypt,
يَتَبَوَّأُ مِنْهَا حَيْثُ يَشَآءُ
(to take possession therein, when or where he likes.) As-Suddi and `Abdur-Rahman bin Zayd bin Aslam said that this part of the Ayah means, "To do whatever he wants therein." Ibn Jarir at Tabari said that it means, "He used to move about freely in the land after being imprisoned, suffering from hardship and the disgrace of slavery." Allah said next,
(We bestow of Our mercy on whom We will, and We make not to be lost the reward of the good doers.) Allah says here, We did not let the patience of Yusuf, from the harm his brothers exerted on him and being imprisoned because of the wife of the `Aziz, to be lost. Instead, Allah the Exalted and Most Honored rewarded him with His aid and victory,
And the reward of the Hereafter is surely better for those who keep fearing Allah.
It means that Allah had already blessed Sayyidna Yusuf (علیہ السلام) with temporal power, wealth and an ideal state - waiting for him were the high ranks of the 'Akhirah as well. Then, it has also been made clear that the rewards and ranks of the present world and the world-to-come were not restricted to Sayyidna Yusuf (علیہ السلام) . This was an open invitation to everyone who elects to believe, abstain from evil and keep fearing Allah.
During his tenure of rule, Sayyidna Yusuf (علیہ السلام) had accomplished great projects designed to bring peace and comfort to the masses of his people. Their parallel would be hard to find. When, according to his interpretation of the dream, seven years of prosperity passed by and the famine set in, Sayyidna Yusuf (علیہ السلام) abandoned eating to his fill. People said: You have the treasures of the land of Egypt in your possession, yet you go hungry? He said: I do this so that the feeling for the hunger of my common people does not disappear from my heart. He even took an administrative step in this matter. The royal cooks were ordered to prepare only one meal a day, at lunch time, so that the residents of the royal pa-lace too could somehow share in the mass hunger of their people!
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 57–60
‘Place in my charge the storehouses of the land.’ (The original Arabic word translated here as storehouses [or granaries] literally means ‘treasure’). Seeing that he had the attention of the king, Joseph made this request to him, so that with the help of government resources he should be empowered to construct large granaries throughout the whole country, where surplus corn acquired from the farmers and could be stored for the first seven years. The king agreed to this and, exercising his constitutional royal authority, gave Joseph all kinds of power to facilitate this task. The king of Egypt was a polytheist. Verse 76 shows that after the appointment of Joseph the religion of the same king prevailed in Egypt for about ten years. This tradition of the Prophet of God shows that acceptance of a subordinate post under a non-Muslim government is not against Islam. On the same basis our predecessors accepted the posts of ‘Qazi’ under tyrant kings. (Tafsir an-Nasafi). What was Joseph’s purpose in assuming authority in Egypt? The information given in the Quran indicates that his purpose seems to have been to save the subjects of God from famine and then, as a result of this, to create opportunities for the Children of Israel to settle in Egypt.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.