Al-Kāfi - Volume 3 > Obligation of Friday Salah (prayer)
Hadith #5

5ـ الْحُسَيْنُ بْنُ مُحَمَّدٍ عَنْ عَبْدِ الله بْنِ عَامِرٍ عَنْ عَلِيِّ بْنِ مَهْزِيَارَ عَنْ فَضَالَةَ عَنْ أَبَانِ بْنِ عُثْمَانَ عَنْ أَبِي الْعَبَّاسِ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ أَدْنَى مَا يُجْزِئُ فِي الْجُمُعَةِ سَبْعَةٌ أَوْ خَمْسَةٌ أَدْنَاهُ.

5. Al-Husayn ibn Muhammad has narrated from ‘Abd Allah ibn ‘Amir from Ali ibn Mahziyar from Fadalah from Aban ibn ‘Uthman from abu al-‘Abbas who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Minimum number of attending people for Friday Salah (prayer) is seven or at least five people.’”