The Ruling on Rinsing the Mouth and Sniffing Water in Ablution and the Full Ritual Bath

Question:
I said: O Shaykh, may Allah guide you, does Allah command one to rinse the mouth or to go? And if we come and then pray? And if one remembers afterwards, does he repeat the prayer?

Answer:
Yes, rinsing the mouth is obligatory in ablution and in the full ritual bath for major ritual impurity, because it is of the exterior, not the interior. The mouth is of the exterior. Therefore, if a fasting person puts something in his mouth, his fast is not broken, because it is in the ruling of the exterior, unless he swallows it. If he swallows it intentionally, he has erred. But as long as it is in his mouth and he does not break his fast, it is in the ruling of the exterior. And the exterior of the body must be washed in major ritual impurity, and it must be washed if it is one of the limbs of ablution. So if a person takes a full ritual bath for major ritual impurity and does not rinse his mouth or sniff water, he must repeat the bath, because it is not complete.
And if he has an excuse for leaving off rinsing the mouth and sniffing water, he performs dry ablution with clean earth. He performs dry ablution, just as if he had a wound in his mouth and could not let water enter it, or in his nose, where water would harm him because of the illness, he performs dry ablution. But if there is no harm in it, and he left it off out of negligence, then his washing is not valid.