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." (Using translation from Ibn Mājah 794)
وَأَبَا هُرَيْرَةَ أَنَّهُمَا سَمِعَا رَسُولَ اللَّهِ ﷺ يَقُولُ وَهُوَ عَلَى أَعْوَادِ مِنْبَرِهِ «لَيَنْتَهِيَنَّ أَقْوَامٌ عَنْ وَدَعِهِمُ الْجُمُعَاتِ أَوْ لَيَخْتِمَنَّ اللَّهُ عَلَى قُلُوبِهِمْ ثُمَّ لَيَكُونُنَّ مِنَ الْغَافِلِينَ»