Allah, the Exalted and Most Honored, criticizes the people of Al-Madinah and the bedouins around it, who did not participate in the battle of Tabuk with the Messenger of Allah ﷺ. They sought to preserve themselves rather than comfort the Messenger ﷺ during the hardship that he suffered in that battle. They incurred a loss in their share of the reward, since,

لاَ يُصِيبُهُمْ ظَمَأٌ

(they suffer neither Zama'), thirst,

وَلاَ نَصَبٌ

(nor Nasab), fatigue,

وَلاَ مَخْمَصَةٌ

(nor Makhmasah), hunger,

وَلاَ يَطَأُونَ مَوْطِئًا يَغِيظُ الْكُفَّارَ

(nor they take any step to raise the anger of disbelievers), by strategies of war that would terrify their enemy,

وَلاَ يَنَالُونَ

(nor inflict), a defeat on the enemy,

إِلاَّ كُتِبَ لَهُمْ

(but is written to their credit) as compensation for these steps that are not under their control, but a consequence of performing good deeds that earn them tremendous rewards,

إِنَّ اللَّهَ لاَ يُضِيعُ أَجْرَ الْمُحْسِنِينَ

(Surely, Allah wastes not the reward of the doers of good.) Allah said in a similar Ayah,

إِنَّا لاَ نُضِيعُ أَجْرَ مَنْ أَحْسَنَ عَمَلاً

(Certainly We shall not make the reward of anyone who does his (righteous) deeds in the most perfect manner to be lost)