"A Bedouin came to the Prophet with a rabbit that he had grilled it and placed it in front of him. The Messenger of Allah refrained from eating, but he told the people to eat. The Bedouin also refrained, and the Prophet said to him: 'What is keeping you from eating?' He said: 'I fast three days of the month.' He said: 'If you was to fast, fast the shining days."' (Using translation from Nasāʾī 2421)
جَاءَ أَعْرَابِيٌّ إِلَى النَّبِيِّ ﷺ بِأَرْنَبٍ قَدْ شَوَاهَا فَوَضَعَهَا بَيْنَ يَدَيْهِ فَأَمْسَكَ رَسُولُ اللهِ ﷺ فَلَمْ يَأْكُلْ وَأَمَرَ الْقَوْمَ أَنْ يَأْكُلُوا وَأَمْسَكَ الْأَعْرَابِيُّ فَقَالَ لَهُ النَّبِيُّ ﷺ «مَا يَمْنَعُكَ أَنْ تَأْكُلَ؟» قَالَ إِنِّي أَصُومُ ثَلَاثَةَ أَيَّامٍ مِنْ الشَّهْرِ قَالَ «إِنْ كُنْتَ صَائِمًا فَصُمِ الْغُرَّ»