Tafsir of Az-Zumar 39:10

{In this world} is connected to ahsanū (did good), not to ḥasanah (a good reward). The meaning is: Those who did good in this world shall have a good reward in the Hereafter, which is entry into Paradise—a reward whose description cannot be fully grasped.

Al-Suddi connected it to ḥasanah, interpreting the "good reward" as health and well-being. If you ask: "If the adverbial phrase is connected to ahsanū, its grammatical role is clear; but what is the meaning of connecting it to ḥasanah? It cannot be an adjective for it because it precedes it." I say: It would be an adjective if it followed it, but since it precedes it, it serves as a clarification of its location. Thus, the precedence does not invalidate the connection, even if the connection is not strictly adjectival.

{And the earth of Allah is vast} means there is absolutely no excuse for those who fall short in doing good. Even if they plead that they are tied to their homelands and countries, and that they are unable to fully devote themselves to doing good or focus their efforts toward it, it is said to them: "The earth of Allah is vast and His lands are many. Do not remain in a state of incapacity; move to other lands." Follow the example of the Prophets and the righteous in their migration to lands other than their own, so that they may increase in goodness upon goodness and obedience upon obedience.

It is also said: This refers to those who were in the land of the polytheists and were commanded to migrate from it, as in His saying: “Was not the earth of Allah vast enough for you to migrate therein?” (An-Nisa: 97). Others say: It refers to the land of Paradise.

{The patient} are those who endured the separation from their homelands and clans, and who endured other things, such as swallowing bitterness and bearing calamities in obedience to Allah and in increasing their good deeds.

{Without account} means they will not be held to account for it. It is said: It means without measure or scale; it is scooped out for them in abundance, which is a metaphor for multiplication. Ibn Abbas (may Allah be pleased with them both) said: "The calculators cannot grasp its calculation, nor can it be known."

The Prophet (peace and blessings of Allah be upon him) said: "Allah will set up the scales on the Day of Resurrection. The people of prayer will be brought and their rewards will be paid in full by the scales. The people of charity will be brought and their rewards will be paid in full by the scales. The people of Hajj will be brought and their rewards will be paid in full by the scales. Then the people of affliction will be brought; no scale will be set up for them, nor will any record be spread out for them. Reward will be poured upon them in abundance. Allah the Almighty says: 'Only those who are patient will be given their reward without account.' (Az-Zumar: 10). So much so that those who enjoyed well-being in this world will wish that their bodies had been cut with scissors because of the excellence they see being given to the people of affliction."

{Say, "Indeed, I have been commanded to worship Allah, [being] sincere to Him in religion. And I have been commanded to be the first of the Muslims." Say, "Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day." Say, "[It is] Allah I worship, sincere to Him in my religion. So worship what you will besides Him." Say, "Indeed, the losers are the ones who will lose themselves and their families on the Day of Resurrection. Unquestionably, that is the manifest loss."}