٣ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ السَّيَّارِيِّ قَالَ كَتَبَ مُحَمَّدُ بْنُ الْفَرَجِ إِلَى الْعَسْكَرِيِّ (عَلَيْهِ السَّلاَم) يَسْأَلُهُ عَمَّا رُوِيَ مِنَ الْحِسَابِ فِي الصَّوْمِ عَنْ آبَائِكَ فِي عَدِّ خَمْسَةِ أَيَّامٍ بَيْنَ أَوَّلِ السَّنَةِ الْمَاضِيَةِ وَالسَّنَةِ الثَّانِيَةِ الَّتِي تَأْتِي فَكَتَبَ صَحِيحٌ وَلَكِنْ عُدَّ فِي كُلِّ أَرْبَعِ سِنِينَ خَمْساً وَفِي السَّنَةِ الْخَامِسَةِ سِتّاً فِيمَا بَيْنَ الأُولَى وَالْحَادِثِ وَمَا سِوَى ذَلِكَ فَإِنَّمَا هُوَ خَمْسَةٌ خَمْسَةٌ قَالَ السَّيَّارِيُّ وَهَذِهِ مِنْ جِهَةِ الْكَبِيسَةِ قَالَ وَقَدْ حَسَبَهُ أَصْحَابُنَا فَوَجَدُوهُ صَحِيحاً قَالَ وَكَتَبَ إِلَيْهِ مُحَمَّدُ بْنُ الْفَرَجِ فِي سَنَةِ ثَمَانٍ وَثَلاثِينَ وَمِائَتَيْنِ هَذَا الْحِسَابُ لا يَتَهَيَّأُ لِكُلِّ إِنْسَانٍ أَنْ يَعْمَلَ عَلَيْهِ إِنَّمَا هَذَا لِمَنْ يَعْرِفُ السِّنِينَ وَمَنْ يَعْلَمُ مَتَى كَانَتِ السَّنَةُ الْكَبِيسَةُ ثُمَّ يَصِحُّ لَهُ هِلالُ شَهْرِ رَمَضَانَ أَوَّلَ لَيْلَةٍ فَإِذَا صَحَّ الْهِلالُ لِلَيْلَتِهِ وَعَرَفَ السِّنِينَ صَحَّ لَهُ ذَلِكَ إِنْ شَاءَ الله.
3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Sayyariy who has said the following: “Muhammad ibn al-Faraj once wrote to al-‘Askariy , asking about what is narrated, for calculating to fast, from his ancestors about the five days of the last year and six days of the coming year. He (the Imam) wrote, ‘It is correct but count five days in every four years and in the sixth year six days in between the first and the new. In those other than this it is five and five.’ Al- Sayyariy has said that this is because of al-Kabisah (calculating system). He has said that our people have calculated it and they found it to be correct.’ He (the narrator) has said that Muhammad ibn al- Faraj wrote to him (the Imam) in the year two hundred thirty eight about this calculation. (The answer said), ‘This calculation is not easy for everyone to follow. This is for those who know the years and that when al-Kabisah year was. Then crescent of the month of Ramadan of the first night is correct for them. Once the crescent of the night is established, then it is correct for them by the will of Allah.’” 