Is intentionally committing a subtle or overt melodic error (lahn) in reciting the Quran—one that does not alter the meaning—considered disbelief (kufr) or does it invalidate the prayer, especially for someone who suffers from obsessive thoughts (waswas) concerning the articulation points of letters (makharij al-huruf)? And must such a person repeat past prayers?

The subtle defect (al-lahn al-khafi) is not considered disbelief (kufr), nor does it invalidate the prayer, nor is it a mockery of the Qur'an. However, it is preferable to pay attention to it for those who are able. The reciter will not be punished for it due to the great difficulty involved. Whoever suffers from whispering (waswasah) concerning pronunciation should turn away from these whispers and focus on contemplating the meanings of the Qur'an and achieving humility (khushu') in prayer, because whispering about the articulation points of letters is one of Satan's traps. Repeating the prayer due to a subtle defect is not legislated. Concealing whispers and calamities does not involve any religiously prohibited matter; rather, it is a sign of perfect patience.