Sure Sad

The summary/theme of the Surah Sad : 

As the Surah begins, the aforementioned meeting is reviewed. Allah says that the actual reason behind the denial by those people is not their own arrogance, jealousy, and insistence on following the blind, but their own arrogance, jealousy, and insistence on following the blind based on the dialogue between the Holy Prophet and the disbelievers.

Lesson learned from Surah Sad : 

1. Many partners in business do injustice to each other; except those who truly believe and do good.  
2. Allah's tested His Prophets عليهم السلام, tests that they passed. We should also be ever ready to be tested by Allah's.  
3. The sustenance of Jannah will never become exhausted.  
4. The people of Jahannam will turn on one another, blaming each other for their doom.  
5. They will also look around to see where the people they assumed to be ‘evil’ were in Jahannam, whereas those were the very people who were on the truth, and they would have been given entry into Jannah.  
6. Never think you’re superior to anyone else.  
7. Allah's is never overcome with emotions such as anger etc. Therefore, never think Allah's is angry with you so He will not accept your du‘'.  
8. Shayṭ'n promised that he shall try to lead each and every human astray.