Dissatisfaction is the door to doubt

Dissatisfaction opens the door that leads to doubt in Allah: in His Decree, in His Wisdom, and in His Knowledge. Rarely is the complainer free from these accompanying doubts that mix within his heart and permeate his being. If he were to delve deep into his self with honest introspection, he would find his faith to be infirm and questionable. Contentment and faith are like brothers that accompany one another; meanwhile, doubt and discontentment have a similar fraternal relationship. Tirmidhi related that the Prophet (bpuh) said:

"If you are able to show contentment with faith, then do so. If not, then verily there is much goodness in patience with that which the self hates."

So those who are dissatisfied are resentful on the inside, and also angry, even if their anger is not expressed in words. Inside them mingles an assortment of questions, such as why has this happened, or how could this be?