What is the ruling on frequently correcting mistakes in the remembrance (dhikr) during prayer and in the recitation of Al-Fatiha—especially concerning the letter "Lām" in the word "Al-Ḍāllīn"—due to a heavy tongue? And is it obligatory to repeat the prayer or perform the prostration of forgetfulness (sujūd al-sahw) because of this? Does the ruling differ if the mistake is in the salutation (taslīm), such as replacing the letter "Mīm" in "ʿalaykum" with a "Bāʾ"?

Summary:

Obsessive thoughts have greatly affected you, and the cure is to completely disregard and ignore them. Regarding the repetition of the letter "L" (lām), do not repeat the recitation or the salutation again due to these obsessive thoughts. A single recitation is sufficient for you. Your complete repetition of the salutation does not invalidate the prayer, nor does it require a prostration of forgetfulness (sujūd as-sahw). If an error occurs in the remembrances of the prayer and you correct it, there is nothing upon you.