Al-Kāfi - The Book of Fasting

َّدُ بْنُ أَبِي عَبْدِ الله عَنْ إِسْحَاقَ بْنِ ٠َّدٍ قَالَ كَتَبْتُ إِلَى أَبِي ٠َّدٍ (عَلَيْهِ السَّلاَ٠َ فَرَضَ الله الصَّوْ٠َ فَوَرَدَ الْجَوَابُ لِيَجِدَ الْغَنِيُّ ٠َضَضَ الْجُوعِ فَيَحِنَّ عَلَى الْفَقِيرِ. 6.

Ali ibn Muhammad and Muhammad ibn abu ‘Abd Allah has narrated from Ishaq ibn Muhammad from Hamzah ibn Muhammad who has said the following: “I once wrote to abu Muhammad (a.s.), and asked, ‘Why has Allah made fasting obligatory?’ The answer was, ‘It is made obligatory so that affluent people can feel the taste of hunger and become compassionate to the poor.’” جهول - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (16/440))