What is the ruling on one who omits gargling and sniffing water into the nose (istīshāq) during a ghusl that is obligatory, or sunnah, or for cleanliness and refreshment (with the intention of removing minor ritual impurity in the latter two), and does he have to repeat the obligatory ghusl and the prayers he performed, and does he only have to repeat the prayers in the case of a sunnah ghusl or a ghusl for cleanliness and refreshment?

Scholars differed concerning the ruling on rinsing the mouth (madmadah) and sniffing water into the nose (istinshāq) in ablution (wudūʾ) and ritual bathing (ghusl). The preponderant opinion is that they are Sunnah, and consequently, ghusl and wudūʾ are valid even if they are omitted. The prayer is therefore valid and does not need to be repeated. As for a recommended or permissible ghusl, it does not suffice for wudūʾ unless the prescribed wudūʾ is performed within it with all its obligatory acts, including intention (niyyah) and sequential order (tartīb).