Does Satan spend the night on the hands or on the nostrils?

The Prophet commanded washing the hands upon waking from sleep and before inserting them into a vessel, three times, out of fear that the hand might have touched dirt or impurity. This is based on his (peace be upon him) saying: "When one of you wakes up from his sleep, he should not dip his hand into the vessel until he washes it three times, for he does not know where his hand spent the night." This prohibition is for purification (tanzīh), not absolute prohibition (taḥrīm), according to the majority of scholars. The wisdom behind the washing is precaution against impurity. As for the devil spending the night in the nostrils, its narration is found in the two Sahih collections with the wording: "When one of you wakes up from his sleep, he should rinse his nose three times, for the devil spends the night in his nostrils." Scholars interpreted this to mean that the nose is an opening through which the devil can reach the heart, and the command to rinse the nose is for recommendation (istiḥbāb), not obligation (wujūb), according to the majority of scholars.