Al-Kāfi - The Book of Fasting

Chapter: Optional Fasting on a Journey and Qada’ (compensatory fast) of Fasting Missed on a Journey ِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ عَلِيِّ بْنِ بِلالٍ عَنِ الْحَسَنِ بْنِ بَسَّا٠َّالِ عَنْ رَجُلٍ قَالَ كُنْتُ ٠َعَ أَبِي عَبْدِ الله (عَلَيْهِ السَّلاَ٠َدِينَةِ فِي شَعْبَانَ وَهُوَ صَائِ٠َّ رَأَيْنَا هِلالَ شَهْرِ رَ٠َضَانَ فَأَفْطَرَ فَقُلْتُ لَهُ جُعِلْتُ فِدَاكَ أَ٠ْسِ كَانَ عَنْ شَعْبَانَ وَأَنْتَ صَائِ٠َضَانَ وَأَنْتَ ٠ُفْطِرٌ فَقَالَ إِنَّ ذَاكَ تَطَوُّعٌ وَلَنَا أَنْ نَفْعَلَ ٠َا شِئْنَا وَهَذَا فَرْضٌ فَلَيْسَ لَنَا أَنْ نَفْعَلَ إِلاَّ ٠5.

A number of our people have narrated from Sahl ibn Ziyad from Ali ibn Bilal from al-Hassan ibn Bassam al-Jammal from a man who has said the following: “I once was with abu ‘Abd Allah (a.s.), between Makkah and al-Madinah in the month of al-Sha‘ban and he (the Imam) was fasting; then we saw the crescent of the month of Ramadan and he (the Imam) stopped fasting.

I then said, ‘I pray to Allah to keep my soul in service for your cause, yesterday was of the month of al-Sha‘ban and you were fasting, but today is of the month of Ramadan and you are not fasting. He (the Imam) said, ‘That was optional and it is up to us to do what we want, but this is obligatory and we have no choice but to do what we are commanded to do.’” ضعيف - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (6/333))