The shaytan's knots on the sleeper's crown

Al-Muwatta relates from Abu Hurayra (may God be pleased with him) that the Prophet ﷺ reported the shaytan ties three knots on the crown of one who sleeps, striking at each knot "your night is long, sleep"; if he wakes and remembers God a knot is loosed, if he performs ablution a knot is loosed, if he prays a knot is loosed, and he rises lively and good-natured ¹ Muwatta 486.

This hadith is among the best-known texts of the shaytan's scheming in sleep; the shaytan besets the sleeper with heedlessness until he rises lazy, and remembrance, ablution and prayer undo his knots ¹. The Sunan rely on it for the fiqh of the pre-dawn meal and night prayer ¹.

Among the reports of devils dealing directly with human beings in the Sunan; this browser shows it in the devils section ¹.