Are the unbefitting suspicions and whisperings about God that afflict the questioner due to his failure and the unanswered prayer for healing—are they satanic whisperings, or do they stem from having ill thoughts (su' az-zann) for which he will be held accountable? And is he, by that, considered a disbeliever (kafir)?

We congratulate you on preserving prayer, Qiyam (night vigil), and supplication. We ask Allah to accept it from you and keep you steadfast. As for obsessive thoughts (waswas), there is no accountability for them as long as you do not utter them. You must turn away from them and seek refuge in Allah. Allah tests His servants with withholding and giving to see their patience and gratitude. Allah's withholding from a believer is a gift, and His trial is a cure. You must be patient and diligent in supplication, and trust in Allah's promise of answering. Do not be hasty or despair. Having a bad opinion of Allah is forbidden. You must repent from it and have a good opinion of Him, for Allah treats His servant according to their opinion of Him. One of the greatest reasons for having a good opinion of Allah is knowing His names, attributes, and His wisdom in giving and withholding.