"Umar, May Allah be pleased with us on the day when we stopped at Al-Qaha?' Abu Dharr said: 'I was. A rabbit was brought to the Messenger Allah and the man who brought it said: I saw it bleeding (menstruating). The Prophet did not eat, then he said: "Eat." A man said: "I am fasting." He said: "What fast are you observing?" He said: "Three days each month" He said: "Why don't yo0u fast the bright shining days, the thirteenth, fourteenth and fifteenth."' (Using translation from Nasāʾī 4311)
قَالَ أَبُو ذَرٍّ أَنَا أُتِيَ النَّبِيُّ ﷺ بِأَرْنَبٍ فَقَالَ الرَّجُلُ الَّذِي جَاءَ بِهَا إِنِّي رَأَيْتُهَا تَدْمَى فَكَأَنَّ النَّبِيَّ ﷺ لَمْ يَأْكُلْ ثُمَّ إِنَّهُ قَالَ «كُلُوا» فَقَالَ رَجُلٌ إِنِّي صَائِمٌ قَالَ «وَمَا صَوْمُكَ؟» قَالَ مِنْ كُلِّ شَهْرٍ ثَلَاثَةُ أَيَّامٍ قَالَ «فَأَيْنَ أَنْتَ عَنِ الْبِيضِ الْغُرِّ ثَلَاثَ عَشْرَةَ وَأَرْبَعَ عَشْرَةَ وَخَمْسَ عَشْرَةَ؟»