because in a standing or sitting posture, the bodily outlet does not open as it does when bowing or prostrating.

A third view is that sleeping while standing, sitting, bowing, or prostrating does not invalidate ablution, unlike sleeping while lying down or in other positions. This is the view of Abū Hanīfa and the third view reported from Ahmad. Ahmad’s position, however, restricts this to light sleep.

Those who hold this view cite a hadith in the Sunan collections:

“Ablution is not required of one who sleeps standing, sitting, bowing, or prostrating, but it is required of one who sleeps lying down.”

For when a person sleeps lying down, his joints relax, allowing a bodily emission to escape. This is unlike standing, sitting, bowing, and prostrating, in which the limbs remain firm rather than relaxed, so there is no cause for anything to pass from the body. Moreover, sleep in these positions is ordinarily light, since a person would fall if he fell deeply asleep. There are two views concerning a seated person whose hands fall to the ground.

The stronger view in this matter is that if someone who has performed ablution is unsure whether his sleep was of a kind that invalidates it, his ablution is not deemed invalid. This is because his state of ritual purity is established with certainty and is not negated by doubt. And Allah knows best.