Why is cotton placed in the mouth and the nose of the deceased?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Some jurists recommended stuffing the deceased’s holes with cotton so as to block the inner liquids and odors. Moreover, they recommended putting perfumes and camphor on the cotton.

Such recommendation was narrated on the authority of some righteous predecessors; Al-Hasan said: "It is recommended to stuff the anus, ears and nose of the deceased."  Ibn Seereen, may Allaah have mercy upon him, also narrated that: "It is recommended to stuff the anus, mouth and nose of the deceased with cotton."  [Ibn Abi Shaybah]

However, there is no evidence supporting this view. Therefore, this should not be applied unless there is fear that something will leak from the body of the deceased; so as to ward off the harm.

The Hanbali scholar, Al-Buhooti, may Allaah have mercy upon him, said: “If there is fear that some blood may come out of his facial apertures like the mouth and nose, there is nothing wrong with stuffing them with cotton to ward off the harm.”

Allaah Knows best.