وَ رَوَى مُوسَى بْنُ بَكْرٍ عَنِ اَلْفُضَيْلِ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: فِي رَجُلٍ عَلَيْهِ صَوْمُ شَهْرٍ فَصَامَ مِنْهُ خَمْسَةَ عَشَرَ يَوْماً ثُمَّ عَرَضَ لَهُ أَمْرٌ فَقَالَ «إِنْ كَانَ صَامَ خَمْسَةَ عَشَرَ يَوْماً فَلَهُ أَنْ يَقْضِيَ مَا بَقِيَ وَ إِنْ كَانَ صَامَ أَقَلَّ مِنْ خَمْسَةَ عَشَرَ يَوْماً لَمْ يُجْزِئْهُ حَتَّى يَصُومَ شَهْراً تَامّاً ».
Musa ibn Bakr narrated from Al-Fudayl, from Abu Abdullah (a.s), regarding a man obligated to fast for a month who completed fifteen days of fasting and then was interrupted by some matter. Imam (a.s) said: "If he has fasted fifteen days, he may make up the remaining days. However, if he has fasted less than fifteen days, it will not suffice him, and he must start anew and fast a complete month."