Is it obligatory to remove minor impurities that may be on the tooth and under the nail if they act as a barrier, and what is the evidence for that?

Slight dirt under the fingernail is excused by many scholars. Ibn Taymiyyah holds that all minor impediments are excused. Those who do not excuse it argue that the area is commanded to be washed, and the obligation is not fulfilled except by washing it. Removing this dirt does not require hardship, and dirt originating from the body, such as dried sweat, is excused. What suffices for the one who suffers from obsessive doubts is to adopt the easiest of the opinions.