Does internal grumbling and impatience with tribulation lead to God's wrath, or is the reward written for the afflicted regardless of their patience?

Patience in the face of affliction and avoiding despair are religiously commanded, serving as a test and trial for the believer. Therefore, it is impermissible for a Muslim to say or do anything that contradicts contentment with Allah's decree, otherwise, they would be disobedient, for Allah's decree is entirely good, just, and wise. If mentioning pain is not a complaint, then what matters is the heart's action, not the tongue's utterance. It is not permissible for the heart to object to Allah's decree unless it is a whisper (waswasah) that one cannot repel, in which case there is no accountability. And it is not considered a lack of contentment to seek to change the affliction through permissible, Shariah-compliant means, such as medical treatment and Ruqyah.