﴿ وَإِذَآ أُنزِلَتْ سُورَةٌ أَنْ ءَامِنُوا۟ بِٱللَّهِ وَجَٰهِدُوا۟ مَعَ رَسُولِهِ ٱسْتَـْٔذَنَكَ أُو۟لُوا۟ ٱلطَّوْلِ مِنْهُمْ وَقَالُوا۟ ذَرْنَا نَكُن مَّعَ ٱلْقَٰعِدِينَ ﴾

“[They are indeed denying it:] for, when they were called upon through revelation, "Believe in God, and strive hard [in His cause] together with His Apostle," [even] such of them as were well able [to go to war] asked thee for exemption, saying, "Allow us to stay behind with those who remain at home!"”

The expression: اُولُوا الطَّولِ (ulu 'at-caul: translated as ` the capable ones' ) (86) is not for particularization. Instead, it serves a purpose. It tells that there were others too, the ones not so capable. And the incapable ones had, at least, some obvious excuse to stay behind.