At Tawbah Ayah 120

مَا كَانَ لِأَهْلِ ٱلْمَدِينَةِ وَمَنْ حَوْلَهُم مِّنَ ٱلْأَعْرَابِ أَن يَتَخَلَّفُواْ عَن رَّسُولِ ٱللَّهِ وَلَا يَرْغَبُواْ بِأَنفُسِهِمْ عَن نَّفْسِهِۦ‌ۚ ذَٲلِكَ بِأَنَّهُمْ لَا يُصِيبُهُمْ ظَمَأٌ وَلَا نَصَبٌ وَلَا مَخْمَصَةٌ فِى سَبِيلِ ٱللَّهِ وَلَا يَطَــُٔونَ مَوْطِئًا يَغِيظُ ٱلْكُفَّارَ وَلَا يَنَالُونَ مِنْ عَدُوٍّ نَّيْلاً إِلَّا كُتِبَ لَهُم بِهِۦ عَمَلٌ صَـٰلِحٌ‌ۚ إِنَّ ٱللَّهَ لَا يُضِيعُ أَجْرَ ٱلْمُحْسِنِينَ ١٢٠ It was not ?proper? for the people of Medina and the nomadic Arabs around them to avoid marching with the Messenger of Allah or to prefer their own lives above his. That is because whenever they suffer from thirst, fatigue, or hunger in the cause of Allah; or tread on a territory, unnerving the disbelievers; or inflict any loss on an enemy—it is written to their credit as a good deed. Surely Allah never discounts the reward of the good-doers.