✅ Answer: Consider the following narrations:

1⃣ عَنْ جَمِیلِ بْنِ صَالِحٍ عَنْ أَبِی الْحَسَنِ مُوسَی أَنَّهُ قَالَ کُلُّ مَنْ عَجَزَ عَنْ نَذْرٍ نَذَرَهُ فَکَفَّارَتُهُ کَفَّارَةُ یَمِینٍ

📚 Al-Kafi, Vol. 7, Page 457

Translation: Imam Kazim (AS) said: Whoever is unable to fulfill a vow they made must offer the expiation (kaffara) of an oath (yameen).

2⃣عَنْ أَبِی عَلِیٍّ الْأَشْعَرِیِّ عَنْ مُحَمَّدِ بْنِ عَبْدِ الْجَبَّارِ وَ عَنْ مُحَمَّدِ بْنِ إِسْمَاعِیلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ جَمِیعاً عَنْ صَفْوَانَ عَنِ ابْنِ مُسْکَانَ عَنِ الْحَلَبِیِّ عَنْ أَبِی عَبْدِ اللَّهِ فِی کَفَّارَةِ الْیَمِینِ یُطْعِمُ عَشَرَةَ مَسَاکِینَ لِکُلِّ مِسْکِینٍ مُدٌّ مِنْ حِنْطَةٍ أَوْ مُدٌّ مِنْ دَقِیقٍ وَ حَفْنَةٌ أَوْ کِسْوَتُهُمْ لِکُلِّ إِنْسَانٍ ثَوْبَانِ أَوْ عِتْقُ رَقَبَةٍ وَ هُوَ فِی ذَلِکَ بِالْخِیَارِ أَیَّ ذَلِکَ شَاءَ صَنَعَ فَإِنْ لَمْ یَقْدِرْ عَلَی وَاحِدَةٍ مِنَ الثَّلَاثِ فَالصِّیَامُ عَلَیْهِ ثَلَاثَةُ أَیَّامٍ

✅ Note 1: The expiation for breaking an oath, applicable to this case, is explained in the following narration:

📚 Al-Kafi, Vol. 7, Page 452

3⃣ عَنْ عَبْدِ اللَّهِ بْنِ سِنَانٍ عَنْ أَبِی عَبْدِ اللَّهِ قَالَ کُلُّ صَوْمٍ یُفَرَّقُ إِلَّا ثَلَاثَةَ أَیَّامٍ فِی کَفَّارَةِ الْیَمِین

Translation: Imam Sadiq (AS) said regarding the expiation of an oath (yameen): One must either feed ten needy people, providing each with a measure (approximately 870 grams) of wheat or flour, or clothe ten needy people (each receiving two garments: a lower and upper garment), or free a slave. The person is free to choose any of these three options. If they are unable to do any of these, they must fast for three days.

✅ Note 2: According to the following narration, these three days of fasting must be consecutive:

4⃣عَنْ أَبِی الصَّبَّاحِ الْکِنَانِیِّ قَالَ سَأَلْتُ أَبَا عَبْدِ اللَّهِ عَنْ رَجُلٍ قَالَ عَلَیَّ نَذْرٌ قَالَ لَیْسَ النَّذْرُ بِشَیْ ءٍ حَتَّی یُسَمِّیَ لِلَّهِ صِیَاماً أَوْ صَدَقَةً أَوْ هَدْیاً أَوْ حَجّاً

📚 Al-Kafi, Vol. 4, Page 140

Translation: Imam Sadiq (AS) said: All fasts can be performed separately, except for the three-day fast as expiation for an oath.

✅ Note 3:

4⃣عَنْ دَاوُدَ بْنِ فَرْقَدٍ عَنْ أَبِی عَبْدِ اللَّهِ فِی حَدِیثٍ قَالَ إِنَّ الِاسْتِغْفَارَ تَوْبَةٌ وَ کَفَّارَةٌ لِکُلِّ مَنْ لَمْ یَجِدِ السَّبِیلَ إِلَی شَیْ ءٍ مِنَ الْکَفَّارَةِ

📚 Al-Kafi, Vol. 7, Page 455

Translation: Kanani reported that he asked Imam Sadiq (AS) about a person who says, 'I have made a vow (عَلَیَّ نَذْرٌ).' The Imam replied: Unless the person specifies that the vow is for the sake of God—such as vowing to fast, give charity, perform a sacrifice, or go on Hajj—the vow is not binding.

Explanation: This means that for a vow to be valid, the phrase 'For God, it is upon me to…' (لله علي) must be explicitly stated. Otherwise, the vow is not legally binding, and breaking it does not require expiation.

..... ثُمَّ قَالَ إِنِّی لَأَکْرَهُ الْإِیجَابَ أَنْ یُوجِبَ الرَّجُلُ عَلَی نَفْسِهِ....

✅ Note 4:

📚 Tahdhib, Vol. 1, Page 164

Translation: Imam Sadiq (AS) said: Seeking forgiveness, repentance, and istighfar serve as a form of expiation for those who cannot afford to fulfill the required expiation.