some arabs of the desert came with ready excuses asking for leave to stay behind. but those who had lied to god and his prophet stayed at home doing nothing. so the punishment for those who disbelieve among them will be painful.
وجاء المعذرون من الأعراب ليؤذن لهم وقعد الذين كذبوا الله ورسوله سيصيب الذين كفروا منهم عذاب أليم