مَا كَانَ لِأَهْلِ الْمَدِينَةِ وَمَنْ حَوْلَهُم مِّنَ الأَعْرَابِ أَن يَتَخَلَّفُواْ عَن رَّسُولِ اللّهِ وَلاَ يَرْغَبُواْ بِأَنفُسِهِمْ عَن نَّفْسِهِ ذَلِكَ بِأَنَّهُمْ لاَ يُصِيبُهُمْ ظَمَأٌ وَلاَ نَصَبٌ وَلاَ مَخْمَصَةٌ فِي سَبِيلِ اللّهِ وَلاَ يَطَؤُونَ مَوْطِئًا يَغِيظُ الْكُفَّارَ وَلاَ يَنَالُونَ مِنْ عَدُوٍّ نَّيْلاً إِلاَّ كُتِبَ لَهُم بِهِ عَمَلٌ صَالِحٌ إِنَّ اللّهَ لاَ يُضِيعُ أَجْرَ الْمُحْسِنِينَ
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سورة التوبة
(9/120) It is not (proper) for the people of Madinah and those surrounding them of the Bedouins that they remain behind after the Messenger of Allah or that they prefer their souls over his soul. This is because there afflicts them not thirst or fatigue or hunger in the Way of Allah, nor do they take any step which enrages the disbelievers, nor do they attain from the enemy what they attain, but an improving deed is written down to them on account of it; surely Allah does not waste the reward of the Muhsînin (good-doers).
Surah At-Tawbah