The (true) believers are those only who believe in Allah and His messenger and afterward doubt not, but strive with their wealth and their lives for the cause of Allah. Such are the sincere.
Times are computed by method; your mosque's timetable governs the adhan. Every text carries its source and grade. Nothing here is a fatwa, a prediction, or a substitute for a doctor: your own scholar decides what is contested, and the tradition itself says the practice is alongside treatment, never instead of it.