Sayyidina Abu Hurayrah (RA) narrated that Allah’s Messenger (SAW) said, “Indeed, your Lord says: every good deed is like ten times to seven hundred times, and the fast is for Me and I give a reward for it. And, fasting is a shield from Hell. And the bad breath of one who is fasting is better in Allah’s sight than the fragrance of musk. If an ignorant person reviles one of you who is fasting then let him say (to him), “I am fasting”.
[Ahmed7793, 9720, Bukhari 1904, Muslim 1151, Ibn e Majah 1638, Nisai 2214]