O you who believe! be careful of (your duty to) Allah and be with the true ones. 119 It did not beseem the people of Medina and those round about them of the dwellers of the desert to remain behind the Apostle 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; 120 Each sum they spend, be it small or large, and each valley they cross is written to their account, so that Allah may recompense them for their best deeds. 121 ۞ With all this, it is not desirable that all of the believers take the field [in time of war]. From within every group in their midst, some shall refrain from going forth to war, and shall devote themselves [instead] to acquiring a deeper knowledge of the Faith and [thus be able to] teach their home-coming brethren, so that these [too] might guard themselves against evil. 122