What are the benefits of believing in divine decree and destiny?

Among the benefits of believing in divine decree (Qada') and destiny (Qadar) is the perfection of faith and the presence of its true taste. This is because a servant will not find the taste of the reality of faith until he knows that what befell him could not have missed him, and what missed him could not have befallen him. Another benefit is the tranquility of the soul, the reassurance of the heart, and steadfastness upon Allah's methodology. Thus, neither will blessings make him boastful, nor will misfortune make him despair, for all the blessings that befall him are from Allah. This belief instilled tranquility and reassurance in the hearts of the righteous predecessors and nurtured them upon dignity and honor.