Is it obligatory for one who has shown displeasure and discontent with Allah to perform ghusl, or is repentance sufficient?

One who is afflicted by waswasah (obsessive whispering) is not obligated to perform ghusl (ritual bath); rather, what is required of him is repentance. A Muslim is not judged to have committed kufr (disbelief) unless he utters a statement, performs an action, or holds a belief of kufr that is proven by the Qur’an, the Sunnah, or the consensus of scholars, and the conditions for deeming one a disbeliever are met and the impediments to it are absent. The questioner must rid himself of these obsessive thoughts. Discontentment (tasakhkhut) in the heart is not of a single degree; some of it can lead to disbelief if its cause is doubt in Allah’s wisdom and justice, or objection to His decree and preordainment. Some of it is less than that if its cause is impatience and pain, alongside submission to Allah. Discontentment with Allah’s decrees through objection and dissatisfaction is considered disbelief. Discontentment is of three types: by the heart (which may lead to disbelief), by the tongue, such as supplicating for woe and destruction, and by the limbs, such as slapping the cheeks and tearing garments, and all of it is forbidden.