Is it permissible for someone afflicted with obsessive doubts (waswas) to invoke the Hadith: "He who falls into doubtful matters falls into that which is unlawful," as a justification for indulging in his obsessive thoughts and repeating ablution to ward off doubtful matters?

The scrupulous person's argument using the aforementioned hadith is incorrect, because the ambiguities in the hadith do not include waswasah (obsessive doubts/whispers), otherwise, the Prophet's (peace be upon him) command to guard against ambiguities would contradict his prohibition of waswasah. The Prophet (peace be upon him) prohibited yielding to waswasah and commanded turning away from it. Scholars have agreed that yielding to waswasah is not a matter of avoiding ambiguities; rather, it is a deception from Satan. Ibn Daqiq al-Eid pointed out that hesitation due to an illusory suspicion is a delusion and a whisper from Satan. The Sharia is built upon ease, not upon opening the door to waswasah, which brings evil.