The virtue of prayer in congregation, and clarifying the stern warning against staying away from it, and that it is fard kifayah
وَحَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ اللَّهِ بْنِ يُونُسَ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا أَبُو إِسْحَاقَ، عَنْ أَبِي الأَحْوَصِ، سَمِعَهُ مِنْهُ، عَنْ عَبْدِ اللَّهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ لِقَوْمٍ يَتَخَلَّفُونَ عَنِ الْجُمُعَةِ " لَقَدْ هَمَمْتُ أَنْ آمُرَ رَجُلاً يُصَلِّي بِالنَّاسِ ثُمَّ أُحَرِّقَ عَلَى رِجَالٍ يَتَخَلَّفُونَ عَنِ الْجُمُعَةِ بُيُوتَهُمْ " .
'Abdullah reported Allah's Messenger (ﷺ) as saying about people who are absent from Jumu'a prayer: I intend that I should command a person to lead people in prayer, and then burn those persons who absent themselves from Jumu'a prayer in their houses.