Are forgetting or repeating the intention (niyyah) or the mention of Allah's name (tasmiyah) during ablution, as well as doubting whether limbs have been washed or forgetting the intended obligatory prayer (fard) during Salah, and the subsequent forced repetition of the intention or takbir, or the feeling of interrupting the prayer upon making a mistake or hearing a sound, symptoms of obsessive-compulsive disorder (OCD), and is prayer invalidated in these cases?

It is not permissible to surrender to obsessive whispers (waswas) in acts of worship, as they are from the stratagems of Satan. Rather, one should remain firm, patient, and adhere to remembrance (dhikr) and prayer. Among the best ways to get rid of them is to completely disregard them and to believe that they are satanic thoughts and to fight them, seeking refuge in Allah and supplicating. Whoever is afflicted by them should trust in Allah and desist. Saying "Lā ilāha illā Allāh" (There is no god but Allah) is recommended for one afflicted by waswas in ablution (wudu) or prayer. The feeling of wanting to stop the prayer due to forgetfulness or hearing a sound is from the waswas that must be disregarded, as forgetfulness does not invalidate the prayer.