In the name of Allah, Most Gracious, Most Merciful.
Abu Hurairah (MAPH) reported: The Messenger of Allah (SAWS) 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).
Abu Hurairah (MAPH) reported: The Prophet (SAWS) said, “If one does not eschew lies and false conduct, Allah has no need that he should abstain from his food and his drink.” (Al-Bukhari).
Commentary Hadith 1: We learn from this Hadith that during Saum not only food, drink and intimate relations with one’s spouse are prohibited but the improper use of the tongue and the other organs of the body as well. When one is observing Saum, he should neither use abusive language nor talk foolishly nor tell lies nor make obscene conversation nor indulge in backbiting nor quarrel with anyone. If someone provokes him, he should keep himself quiet and remember that he is observing Saum and he has to abstain from such things. As far as possible, he should keep his tongue engaged in the remembrance of Allah and recitation of the Quran.
Commentary Hadith 2: This Hadith exhorts those observing Saum to fulfill all the requirements of fasting. One should not conduct himself in such a manner that on the one side he observes Saum and on the other he is fearless of Allah. To save himself from Allah’s Wrath and to get the reward of the fasts, one must abstain from all sorts of vices, such as cheating, lying, backbiting, and using obscene language. The threat held against such people in this Hadith should make them fear that their Saum will go to waste and they would be deprived of its reward. It does not mean that such people should start eating and drinking during Saum but what is intended is that they should save themselves from all kinds of sins so that they may earn the reward of Saum.
SAWS: May Allah exalt his mention and protect him from imperfection
MAPH: May Allah be pleased with him
Riyaadiss-Saliheen (The Meadows of the Righteous)
By Imam An Nawawi
Hadith 1: Chapter 223, Page 360, No 1240
Hadith 2: Chapter 223, Page 361, No 1241