إِنَّمَا يَسْتَأْذِنُكَ الَّذِينَ لَا يُؤْمِنُونَ بِاللَّهِ وَالْيَوْمِ الْآخِرِ وَارْتَابَتْ قُلُوبُهُمْ فَهُمْ فِي رَيْبِهِمْ يَتَرَدَّدُونَ
“No one would ask for exemption except those who have no faith in Allah or the Last Day, and whose hearts are in doubt, so they are torn by their doubts.”
Part of the well-established hypocrites-who-stayed-behind-from-Tabuk passage of Surat al-Tawbah.