عَنْ رَجُلٍ مِنْ بَنِي تَمِيمٍ، قَالَ: كُنَّا عِنْدَ بَابِ مُعَاوِيَةَ بْنِ أَبِي سُفْيَانَ رَضِيَ اللَّهُ عَنْهُ وَفِينَا أَبُو ذَرٍّ رَضِيَ اللَّهُ عَنْهُ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يَقُولُ: ((صَوْمُ شَهْرِ الصَّبْرِ وَثَلَاثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ صَوْمُ الدَّهْرِ، وَيُذْهِبُ مَغَلَّةَ الصَّدْرِ))، قَالَ: قُلْتُ: وَمَا مَغَلَّةُ الصَّدْرِ؟ قَالَ: ((رِجْسُ الشَّيْطَانِ))
It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: The fasts of the month of patience, that is, Ramadan, and then three fasts of every month are equal to the fasts of the whole year; through them, the impurity of the chest is removed. I asked: What is meant by the impurity of the chest? He said: The filth of Satan.