لَا يُقَـٰتِلُونَكُمْ جَمِيعًا إِلَّا فِى قُرًى مُّحَصَّنَةٍ أَوْ مِن وَرَآءِ جُدُرٍۭ ۚ بَأْسُهُم بَيْنَهُمْ شَدِيدٌ ۚ تَحْسَبُهُمْ جَمِيعًا وَقُلُوبُهُمْ شَتَّىٰ ۚ ذَٰلِكَ بِأَنَّهُمْ قَوْمٌ لَّا يَعْقِلُونَ
Laa yuqaatiloonakum jamee'an illaa fee quram muhas sanatin aw minw waraaa'i judur; baasuhum bainahum shadeed; tahsabuhum jamee'anw-wa quloobuhum shatta; zaalika biannahum qawmul laa ya'qiloon
They will not fight you all together except from within fortified towns or from behind walls. Their hostility among themselves is fierce. You think them united, but their hearts are scattered. That is because they are a people who do not reason.
Baʾs is strength in fighting, and commentators took baʾsuhum baynahum in two directions: the hostility these allies bear toward one another, or a courage that holds only while they are among themselves and nobody is facing them. Two consecutive verses end on the same frame, qawmun lā, and change only the verb: 59:13 has yafqahūn, failing to grasp whom to fear, and this verse has yaʿqilūn, failing to reason out what their own divisions mean.