Is it permissible for a fasting person to limit washing the mouth and rinsing the nose to only once during ablution, out of fear of invalidating the fast, instead of three times?

A fasting person is like any other person regarding the ruling on rinsing the mouth and nose. It is recommended for him to rinse his mouth three times and his nose three times, but without exaggeration, based on the Prophet's (peace be upon him) saying: "And exaggerate in sniffing water (into the nose) unless you are fasting." Exaggeration means drawing water into the deepest part of the nose with one's breath. It is legislated for the fasting person to rinse the mouth and nose, by scholarly consensus, but exaggeration in these acts is prohibited for the fasting person for fear of water reaching the stomach. The fundamental act of rinsing the mouth and nose, without exaggeration, does not entail any prohibited consequence.