Tafsir of Al-An'am 6:48

(And We do not send the messengers) to the nations (except as bringers of glad tidings) to those among them who obey, with reward, (and as warners) to those among them who disobey, with punishment. Some have restricted this to Paradise and Hell, because they are the greatest things with which one can be given glad tidings and warned. The two conjoined elements are in the accusative case as intended states (hal) that imply causality. The present tense form is used to signal that this is a continuous matter according to the divine custom.

The verse is connected to His, the Exalted’s, saying: (And they said, "Why has a sign not been sent down to him from his Lord?") That is: We do not send the messengers except for the purpose that they may bring glad tidings to their people of the reward for obedience and warn them of the punishment for disobedience; We did not send them so that they might be challenged with suggestions or mocked.

(So whoever believes) in what is mandatory to believe, (and reforms) what is mandatory to reform and bring forth in accordance with the Sharia. The fa (So) is for the sequence of what follows it upon what preceded it. Man (whoever) is a conjunctive noun, and due to the resemblance of the conjunctive noun to the conditional, the fa is introduced in His, the Exalted’s, saying: (no fear will be upon them) of the punishment which the messengers warned against, (nor will they grieve) over the loss of the reward of which they were given glad tidings. Discussion of this verse has preceded more than once. The three pronouns returning to man are pluralized in consideration of its meaning, just as the two preceding pronouns were singularized in consideration of its wording.