Allaah causes trials and tests to occur upon the people- upon the Muslims and the believers- in order to distinguish the truthful one from the liar, the true believer from the hypocritical liar, and the good one from the wicked one...

 

Shaykh  Fawzaan stated:

“Clear distinction is not attained except when trials and tribulations occur, the true believers  are the firm and steadfast while the deceptive hypocrites stumble.

Kitaabul Kabaa’ir  554-555

From the Article: Trials Distinguish The Truthful Ones From The Liars- By Shaikh Fawzaan

For further reading see here>>https://salaficentre.com/2017/02/26/trials-distinguish-truthful-ones-liars-shaikh-fawzaan/