Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) said: "Allah Almighty says: Every deed of the son of Adam is rewarded from ten times up to seven hundred times, except for fasting, for it is for Me and I Myself will give its reward. Fasting is a shield; so whoever is fasting should not use foul language or act ignorantly. If someone abuses him or hurts him, he should say: I am fasting, I am fasting."
Hadith Referenceصحیح ابن حبان / كتاب الصوم / 3416
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: م.فضيلة الشيخ العلّامة شُعيب الأرناؤوطNull