Congregational Prayer and Its Virtue
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 57
وَ رَوَى اَلْحُسَيْنُ بْنُ عَبْدِ اَللَّهِ اَلْأَرَّجَانِيُّ عَنْهُ عَلَيْهِ اَلسَّلاَمُ أَنَّهُ قَالَ: «مَنْ صَلَّى فِي مَسْجِدِهِ ثُمَّ أَتَى مَسْجِداً مِنْ مَسَاجِدِهِمْ فَصَلَّى مَعَهُمْ خَرَجَ بِحَسَنَاتِهِم.
Al-Hussain ibn Abdullah al-Arrajani narrated from Imam عليه السلام who said: "Whoever prays in his own mosque and then goes to one of their mosques and prays with them, he will leave with the reward of their good deeds."
- Ṣaḥīḥ al-Faqīh, p. 58