It did not beseem the people of Medina and those round about them of the dwellers of the desert to remain behind the Messenger of Allah, nor should they desire (anything) for themselves in preference to him; this is because there afflicts them not thirst or fatigue or hunger in Allah's way, nor do they tread a path which enrages the unbelievers, nor do they attain from the enemy what they attain, but a good work is written down to them on account of it; surely Allah does not waste the reward of the doers of good;

So that Allah will do away with the worst of what they did and give them their reward for the best of what they do.