Tafseer : At-Tawbah 90

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,

and 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,

a painful torment will seize those of them who disbelieve.