﴿He admits whom He wills﴾ means from His knowledge, those deserving of happiness. He is not unjust. ﴿Into His mercy﴾ by His wisdom, so He facilitates for him the taking of the path that leads to Him by granting him success in justice, and He prepares for him a great reward.

And when the people of justice are given glad tidings with the present tense verb indicating continuity, and He did not make it past tense so that a stubborn person among those who are engaged in misguidance does not say: I am not suitable because He did not admit me, He added to it what is for their opposites in a verbal sentence built on the past, informing that their punishment is present, having been completed. [He said-]: ﴿And the wrongdoers﴾ means, and He has humiliated those who are accustomed to walking in ways not pleasing, like one walking in darkness. So He admits them into His wrath, and He has ﴿prepared for them﴾ (p-163) [that is-] a preparation that He has decreed with His greatness, so it is not to be increased or decreased ever ﴿a painful punishment﴾. The verse is from the type of interweaving: it mentioned admission and mercy first as an indication of the opposite second, and punishment second as an indication of reward first. The secret of that is that what He mentioned is more deserving of encouraging the people of justice in it, even if their situation is bad in this world, and of frightening the people of injustice from it, even if their situation is good in this world. This latter detailed return leads to happiness and misery, as the first indicates that man is given utmost attention, and that he was created only for testing. So he is either a disbeliever, upon whom is wrath, or a grateful one, looked upon with the eye of pleasure. So glorified is He who created us, causes us to die, and gives us life by His power, and Allah is the Guide.