In the opening statement of the last verse of the Surah, it was said:

لَقَدْ كَانَ فِي قَصَصِهِمْ عِبْرَ‌ةٌ لِّأُولِي الْأَلْبَابِ

Surely, in the narratives of these, there is lesson for the people of understanding - 111.

This statement may be pointing to the stories of all prophets (علیہم السلام) in the Qur'an and also to the particular story of Sayyidna Yusuf (علیہ السلام) which has been narrated in this Surah - because, through this later event, it has become absolutely clear that the obedient servants of Allah are supported and helped in so many ways when they are taken out from a deep well and made to sit on a high throne and are rescued from the threat of disgrace all the way to the zenith of the finest in grace and honour, not to mention the practitioners of ill-will and deception who ultimately end up in sheer shame.

Said next is:

مَا كَانَ حَدِيثًا يُفْتَرَ‌ىٰ وَلَـٰكِن تَصْدِيقَ الَّذِي بَيْنَ يَدَيْهِ

It is not an invented story, rather, a confirmation of what has been before it ...,

that is, of the books revealed before it - because, this story of Sayyidna Yusuf (Joseph) (علیہ السلام) has been mentioned in the Torah and the Injil as well. And Hadrat Wahb ibn Munabbih says: There is no Scripture which does not have the story of Sayyidna Yusuf (علیہ السلام) in it. (Mazhari)

And in the last sentence of the verse, it is said: وَتَفْصِيلَ كُلِّ شَيْءٍ وَهُدًى وَرَ‌حْمَةً لِّقَوْمٍ يُؤْمِنُونَ , that is, this Qur’ an is ` an elaboration of everything' (which means that the Qur’ an has details of everything which human beings need in religion - in fields like ` Ibadat (worship of Allah), dealings, morals, social living, government, politics and many others, including injunctions and instructions about all individual and collective concerns of human life - they are all there).

Then, it was said that this Qur'an is ` guidance and mercy for a people who believe.' The restriction of those who have 'Iman or Faith has been placed here because its benefit can be enjoyed by only those who believe. It goes without saying that, though the Qur'an is nothing but mercy and guidance for disbelievers as well, but it is due to their own misconduct and disobedience that this mercy and guidance has become heavy and unwholesome for them.

Shaykh Abu al-Mansur has said: The purpose behind the whole Surah Yusuf and the story of Sayyidna Yusuf (علیہ السلام) narrated therein is to comfort the Holy Prophet ﷺ `. All this is to tell him that his sufferings at the hands of his people have been the lot of past prophets too. But, in the end, Allah Ta` ala enabled his prophets to overcome - and in his case too, this is what was going to happen.