Al-Kāfi
Hadith 86217- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ مَحْبُوبٍ عَنْ جَمِيلِ بْنِ صَالِحٍ عَنْ أَبِي الْحَسَنِ مُوسَى (عَلَيْهِ السَّلام) أَنَّهُ قَالَ كُلُّ مَنْ عَجَزَ عَنْ نَذْرٍ نَذَرَهُ فَكَفَّارَتُهُ كَفَّارَةُ يَمِينٍ.
17. Ali ibn Ibrahim has narrated from his father from ibn Mahbub from Jamil ibn Salih from abu al-Hassan Musa (a.s.), who has narrated the following: “Abu al-Hassan (a.s.), has said, ‘Whoever makes a vow and commitment to fast and then fails to do so, the expiation on him is like the Kaffarah (expiation) for an oath.’”