Sadness in Islam
Islam is a religion that respects human nature. Allah is aware of the emotions that people experience. For example, sadness has a place in Islam and it is not discouraged to experience it.
There are several stories of Islam in which we see that there was sadness. These stories provide validation that it is okay to experience sadness. The Prophet (ﷺ) experienced this, his Sahaba and the scholars after them.
It is a natural emotion to be sad. This happens in the event of an accident, trauma, injustice and various other situations.
Moreover, Muslims are forgiven of their sins when they experience a difficult situation, grief or worry.
The Prophet (ﷺ) said: “Never is a believer afflicted with discomfort, hardship, sickness, sorrow, and even worry, except that his sins are thereby forgiven.” [Sahih Muslim 2573]
In grief, that thought often automatically comes to mind, even if you try to stop it. It is a thought that tries to come up with a logical or reasonable explanation to why you are in pain.
Allah tests anyone with a calamity or difficulty that causes grief. In reality, He wants the best for the people. He expresses this in several verses of the Quran.
Allah wishes for you ease and He does not wish for you inconvenience.
Allah wishes to lighten (the burden) for you; and man is created weak.
You will not be tested beyond your ability
It can sometimes become so difficult that you feel that it is beyond your ability to deal with it. That happens when the test is very hard. But Allah says that no one is tested beyond his ability.
Allah burdens no one beyond his ability.