communal responsibility in defense

۞ قَدْ يَعْلَمُ ٱللَّهُ ٱلْمُعَوِّقِينَ مِنكُمْ وَٱلْقَآئِلِينَ لِإِخْوَٰنِهِمْ هَلُمَّ إِلَيْنَا ۖ وَلَا يَأْتُونَ ٱلْبَأْسَ إِلَّا قَلِيلًا

Already Allāh knows the hinderers among you and those [hypocrites] who say to their brothers, "Come to us," and do not go to battle, except for a few,