Is the sniffing out ( الاستنثار ) mentioned in the Hadith necessitated by performing a complete ablution (wudu'), or is sniffing out alone sunnah for one who wakes up from sleep even if not for prayer, and is it legislated for a menstruating woman to do that?

Scholars have differed on two views regarding istinthar (expelling water from the nose) upon waking up:

1. Some scholars understood it to be intended when performing wudu' (ablution), citing the narration from Al-Bukhari: "When one of you wakes up from his sleep and performs ablution, let him blow his nose three times, for Satan spends the night on his nasal passage." 2. Others held the view that istinthar is legislated for everyone who wakes up from nighttime sleep, regardless of whether they perform wudu' or not; this is based on the generality of the narration from Muslim, and because the reason given in the Prophet's (peace be upon him) saying, "for Satan spends the night on his nasal passage," is general.

Accordingly, everyone who wakes up from sleep should perform istinthar to remove the effect of Satan from their nose. If they are going to perform wudu', then the command for istinthar is even more emphasized at that time.