Riyad as-Salihin, Book 9, Hadith 1240 (In-Book)

Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah said, "When any one of you is observing Saum (fasting) on a day, he should neither indulge in obscene language nor should he raise the voice; and if anyone reviles him or tries to quarrel with him he should say: 'I am observing fast."'[Al-Bukhari and Muslim].

عن أبي هريرة رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم‏:‏ ‏ "‏إذا كان يوم صوم أحدكم فلا يرفث ولا يصخب، فإن سابه أحد أو قاتله، فليقل‏:‏ إني صائم‏" ‏

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