حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، عَنْ سُفْيَانَ، عَنْ أَبِي إِسْحَاقَ، عَنْ حَارِثَةَ، قَالَ جَاءَ نَاسٌ مِنْ أَهْلِ الشَّامِ إِلَى عُمَرَ رَضِيَ اللَّهُ عَنْهُ فَقَالُوا إِنَّا قَدْ أَصَبْنَا أَمْوَالًا وَخَيْلًا وَرَقِيقًا نُحِبُّ أَنْ يَكُونَ لَنَا فِيهَا زَكَاةٌ وَطَهُورٌ قَالَ مَا فَعَلَهُ صَاحِبَايَ قَبْلِي فَأَفْعَلَهُ وَاسْتَشَارَ أَصْحَابَ مُحَمَّدٍ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَفِيهِمْ عَلِيٌّ رَضِيَ اللَّهُ عَنْهُ فَقَالَ عَلِيٌّ هُوَ حَسَنٌ إِنْ لَمْ يَكُنْ جِزْيَةً رَاتِبَةً يُؤْخَذُونَ بِهَا مِنْ بَعْدِكَ‏.‏

It was narrated that Ibn al-Hawtakiyyah said

Some food was brought to 'Umar bin al-Khattab and he called a man to join him, but he said, I am fasting. ['Umar] said: What fast are you observing? Were it not for fear of adding or subtracting something, I would have narrated to you a hadeeth, from the Prophet (ﷺ), when the Bedouin brought him a rabbit; rather send for 'Ammar. When 'Ammar came, he said: Were you there on the day when the Bedouin brought the rabbit to the Messenger of Allah (ﷺ)? ('Ammar) said: Yes. ('Umar] said: I saw blood on it, but he (the Prophet (ﷺ) said: `Eat it.` (The Bedouin) said: I am fasting. (The Prophet (ﷺ) said: `What fast are you observing?” He said: The beginning and end of the month. He said: “If you want to fast, then fast the thirteenth, fourteenth and fifteenth (of the month).`