عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: أَتَى أَعْرَابِيٌّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ بِأَرْنَبٍ قَدْ شَوَاهَا وَمَعَهَا صِنَابُهَا وَأُدَمُهَا، فَوَضَعَهَا بَيْنَ يَدَيْهِ فَأَمْسَكَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ فَلَمْ يَأْكُلْ، وَأَمَرَ أَصْحَابَهُ أَنْ يَأْكُلُوا فَأَمْسَكَ الْأَعْرَابِيُّ، فَقَالَ لَهُ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((مَا يَمْنَعُكَ أَنْ تَأْكُلَ؟)) قَالَ: إِنِّي أَصُومُ ثَلَاثَةَ أَيَّامٍ مِنَ الشَّهْرِ، قَالَ: ((إِنْ كُنْتَ صَائِمًا فَصُمِ الْأَيَّامَ الْغُرَّ))
Syedna Abu Hurairah, may Allah be pleased with him, narrates that a Bedouin brought a roasted rabbit to the service of the Messenger of Allah, peace and blessings be upon him, along with a sauce of mustard and raisins and some curry. He placed it before the Prophet, but the Messenger of Allah, peace and blessings be upon him, did not eat it himself; rather, he instructed his companions to eat. The Bedouin refrained from eating. The Messenger of Allah, peace and blessings be upon him, asked him: Why are you not eating? He replied: I fast three days every month (and today I am fasting). The Prophet, peace and blessings be upon him, said: If you wish to fast, then fast on the white days.