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

Some jurists have recommended stuffing the openings of the deceased with cotton to conceal odor or prevent discharge, and placing perfuming substances (hanut) and camphor therein. This has been reported from some of the Salaf, but no legal evidence has been established for it. Therefore, it is not legislated to do so, except when there is fear of something exiting the deceased, in order to avert harm.