Chapter on the Recommended Fasts of the Year
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 2|Chapter 4
وَ رَوَى دَاوُدُ اَلرَّقِّيُّ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: «لَإِفْطَارُكَ فِي مَنْزِلِ أَخِيكَ أَفْضَلُ مِنْ صِيَامِكَ سَبْعِينَ ضِعْفاً أَوْ تِسْعِينَ ضِعْفاً ».
It is narrated by Dawud al-Raqqi from Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq عليه السلام), Imam عليه السلام said: "Breaking your fast at your brother's home is better than fasting seventy or even ninety times."
- Ṣaḥīḥ al-Faqīh