Concise Quran Commentary
It is not for the people of Medina, or those around them of the people who live in the desert, to stay behind the Messenger of Allah (peace be upon him)if he himself goes out to fight, or to be stingy with themselves and give preference to their own safety over the safety of the Messenger (peace and blessings be upon him). Rather, they should sacrifice themselves for him. This is because they suffer no thirst, tiredness or hunger for the sake of Allah, and do not step anywhere in the land of those who deny the truth with their own feet or the hooves of their horses or camels, angering thereby those who oppose the truth, and do not make a gain over their enemy, killing or capturing them, making war gains or defeating them, except that Allah records for them the reward of a good action for them, which He accepts from them. Allah does not allow the reward of those who do good to be lost. Rather, He gives it to them in full, and increases the reward for them.