It wasnarrated from Abu Hurairah that the Messenger of Allah (ﷺ)said:
"When anyone of you is fasting, let him not utter evil orignorantspeech. If anyone speaks to him in an ignorant manner, lethim say:'I am fasting.'" (IT)
English reference (IT): Vol. 1, Book 7, Hadith 1691 (IT)
Arabic reference (IT): Book 7, Hadith 1761 (IT)