"Whoever performs ablution should put water in his nose and then blow it out."

Al-Hasan said, “There is no harm for a person observing Saum (fast) (in this respect). Al-Hasan said, “There is no harm for a person observing Saum (fast) to use snuff if it does not reach the throat, or to smear his eyes with kohl.” ‘Ata’ said, “If a person observing Saum (fast), after rinsing his mouth with water, throws it out, then; there is no harm, unless he swallows his saliva and what is left in his mouth.” And he should not chew gum, for if he swallows his saliva, I do not say that it will break his Saum (fast), but it is prohibited, and if, during the putting of water in the nose and then blowing it out, some water enters the throat and he is unable to bring it back, there is no harm in that.”