He was asked about nosebleeds:

Do they invalidate ablution or not?

He answered:

It is preferable to perform ablution after a nosebleed, but it is not obligatory according to the stronger of the two scholarly opinions.

He was asked:

Does sleeping while seated invalidate ablution? If a man sits with his knees drawn up and held by his hands, then dozes off, his grip loosens, his hand falls to the ground, and he leans over without his side reaching the ground, must he perform ablution or not?

He answered:

Praise be to Allah.

Light sleep while seated with one’s buttocks firmly planted does not invalidate ablution according to the great majority of scholars, including the four imams and others. In their view, sleep is not itself a state of ritual impurity, but rather a circumstance in which ritual impurity may occur, as indicated by the hadith in the Sunan collections:

“The eye is the tie that keeps the anus closed; when both eyes sleep, the tie comes loose.”

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