Musannaf Ibn Abi Shaybah

Hazrat Abu Huraira narrates that when a fasting person rinses his mouth at the time of breaking the fast, he should not spit it out but swallow it.

Hazrat Mughira says that I asked Ibrahim about this matter, so he said that there is no harm in spitting it outside.

Hazrat Umar says that this Ummah will remain upon goodness as long as it hastens to break the fast. If someone is fasting, at the time of iftar, he should rinse his mouth and not throw it out, rather swallow it, because its beginning is goodness.

Hazrat Ata considered rinsing the mouth (with water) at the time of iftar to be disliked (makruh).

Hazrat Aamir says that there is no harm in rinsing the mouth at the time of breaking the fast.

Hasan considered it disliked that a person should rinse his mouth when about to drink something at the time of breaking the fast.

Hazrat Hakam was asked about a fasting person rinsing the mouth, so he considered it disliked (makruh).

Hazrat Sha'bi has declared rinsing the mouth (during fasting) as disliked (makruh) for the fasting person.