Optimism and Trust
The Flowers Of Guidance Volume One Nine Instructive Steps to Gaining Knowledge Step 7: Happiness and Kindness

Another factor in creating happiness is being optimistic towards others and trusting the creatures of God. The practical aspect of being optimistic is “considering everything to be true,” which is a rule of religion in Islam. One must consider everything to be valid unless it is proven to be otherwise. Some people believe the contrary, meaning they do not consider everything to be valid until proven to be accurate, meaning they are pessimistic and untrusting.