The Funeral Prayer (Salat Al-Janazah)
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 26
وَ سَأَلَ اَلْيَسَعُ بْنُ عَبْدِ اَللَّهِ اَلْقُمِّيُّ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلرَّجُلِ يُصَلِّي عَلَى اَلْجِنَازَةِ وَحْدَهُ قَالَ «نَعَمْ» قُلْتُ فَاثْنَانِ يُصَلِّيَانِ عَلَيْهَا قَالَ «نَعَمْ وَ لَكِنْ يَقُومُ اَلْآخَرُ خَلْفَ اَلْآخَرِ وَ لاَ يَقُومُ بِجَنْبِهِ.
Al-Yasa' ibn Abdullah al-Qummi asked Imam Jafar ibn Muhammad Al-Sadiq عليه السلام about a man praying over a funeral alone. Imam عليه السلام replied: "Yes, he may do so." I then asked: "What if there are two people praying?" The Imam said: "Yes, but one should stand behind the other, not next to him."
- Ṣaḥīḥ al-Faqīh