The Sufficient (Vol 4) · Hadith 478 (#Ḥadīth #7)
Chapter 42 | The Case of One Who Wakes up in the Morning with an Intention to Fast, but Who Does Not Do So or Vice Versa when Fasting Is a Compensatory Fast for the Missed Fast in the Month of Ramadan or Other Days
7ـ أَحْمَدُ بْنُ مُحَمَّدٍ عَنِ ابْنِ فَضَّالٍ عَنْ صَالِحِ بْنِ عَبْدِ الله الْخَثْعَمِيِّ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلاَم) عَنِ الرَّجُلِ يَنْوِي الصَّوْمَ فَيَلْقَاهُ أَخُوهُ الَّذِي هُوَ عَلَى أَمْرِهِ أَ يُفْطِرُ قَالَ إِنْ كَانَ تَطَوُّعاً أَجْزَأَهُ وَحُسِبَ لَهُ وَإِنْ كَانَ قَضَاءَ فَرِيضَةٍ قَضَاهُ.
7. Ahmad ibn Muhammad has narrated from ibn Faddal from Salih ibn ‘Abd Allah al-Khath’amiy who has said the following: “I once asked abu ‘Abd Allah , about a man who decides to fast, then he meets his brother who believes as he does; if he can discontinue his fast. He (the Imam) said, ‘If it is optional it will be counted as one day of fasting in his favor, but if it is obligatory Qada’ (compensatory fast), he must do its Qada’ (compensatory fast).”’
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).