They heard the Prophet say on his pulpit: "People should desist from failing to attend the congregations, otherwise Allah will seal their hearts, and they will be among the negligent."
أَخْبَرَنِي ابْنُ عَبَّاسٍ وَابْنُ عُمَرَ أَنَّهُمَا سَمِعَا النَّبِيَّ ﷺ يَقُولُ عَلَى أَعْوَادِهِ لَيَنْتَهِيَنَّ أَقْوَامٌ عَنْ وَدْعِهِمُ الْجَمَاعَاتِ أَوْ لَيَخْتِمَنَّ اللَّهُ عَلَى قُلُوبِهِمْ ثُمَّ لَيَكُونُنَّ مِنَ الْغَافِلِينَ