Allah says; وَجَاء الْمُعَذِّرُونَ مِنَ الَاعْرَابِ لِيُوْذَنَ لَهُمْAnd those who made excuses from the Bedouins came asking your permission to exempt them (from the battle),Allah describes here the condition of the Bedouins who lived around Al-Madinah, who asked for permission to remain behind from Jihad when they came to the Messenger to explain to him their weakness and inability to join the fighting.Ad-Dahhak said that Ibn Abbas said that;they were those who had valid excuses, for Allah said next,وَقَعَدَ الَّذِينَ كَذَبُواْ اللّهَ وَرَسُولَهُand those who had lied to Allah and His Messenger sat at home,and did not ask for permission for it;and Allah warned them of painful punishment,سَيُصِيبُ الَّذِينَ كَفَرُواْ مِنْهُمْ عَذَابٌ أَلِيمٌa painful torment will seize those of them who disbelieve