Does dried nasal mucus in the nose constitute a barrier preventing water from reaching the inside during ablution, based on the opinion that sniffing water into the nose (istinsḥāq) is obligatory?

The ruling concerning dry nasal mucus differs. If it prevents water from reaching the skin, then the istanshaq (sniffing water into the nose) is still valid, and it is not a condition for the water to reach all parts of the inner nose. As for the majority of scholars, istanshaq is a sunnah (recommended act) in wudu (ablution), and wudu is not invalidated by omitting it. It is permissible to follow the opinion of the majority, especially for those afflicted with waswasa (obsessive doubts). It is advisable to ignore waswasa.