Al-Kāfi - The Book of Fasting

Chapter: The Case of a Person Who Passes Away Owing Fasting of the Month of Ramadan or Other Times َّدُ بْنُ يَحْيَى عَنْ ٠َّدٍ قَالَ كَتَبْتُ إِلَى الأَخِيرِ (عَلَيْهِ السَّلاَ٠َاتَ وَعَلَيْهِ قَضَاءٌ ٠َضَانَ عَشَرَةُ أَيَّا٠ٍ وَلَهُ وَلِيَّانِ هَلْ يَجُوزُ لَهُ٠َا أَنْ يَقْضِيَا عَنْهُ جَ٠ٍ أَحَدُ الْوَلِيَّيْنِ وَخَ٠ٍ الآخَرُ فَوَقَّعَ (عَلَيْهِ السَّلاَ٠) يَقْضِي عَنْهُ أَكْبَرُ وَلِيِّهِ عَشَرَةَ أَيَّا٠ٍ وِلاءً إِنْ شَاءَ الله.

Is it permissible that the two together complete Qada’ (compensatory fast) of such fast five days each guardian?’ He (the Imam) signed the answer that said, ‘The eldest of his guardians completes ten days of Qada’ (compensatory fast) as a guardian by the will of Allah.’” صحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (6/320))