Tafsir of Al-A'la 87:9

{ So remind, if the reminder should benefit } means: Remind the people as We have facilitated for you, by that which is revealed to you, and guide them to the religious rulings contained within it, just as you have been doing. It is also said that it means: Remind after it has been established, meaning after the matter has been made straight and prepared for you. So if he desires [the reminder], then persist in reminding after the matter has been straightened for you in terms of your recitation of the revelation and your teaching of the Quran, such that you do not forget anything of it except that which the interest necessitates forgetting, and the facilitation for you of the easy way in every aspect of the religion; then that is it, otherwise it is nothing.

The restriction of the reminder to the benefit of the reminder is because the Messenger of Allah, may Allah exalt him and grant him peace, had already reminded and exerted himself to the utmost in doing so; he left no stone unturned and followed every path, leaving no place or highway, out of his eagerness for their belief and their unification of the Sovereign Judge. Yet, this only increased some people in disbelief, stubbornness, and corruption. Thus, he was commanded—as a relief to him, for the eagerness for their belief was almost directing the arrows of destruction toward him, as the Almighty said: "Then perhaps you would kill yourself through grief over them, [O Muhammad], if they do not believe in this message"—to restrict the reminder to instances where it is generally beneficial; that is, that the one whom he reminds be, in whole or in part, someone from whom benefit is hoped. He should not weary his noble self in reminding those whom reminder only causes to increase in insolence, aversion, corruption, and arrogance—those whose hearts are sealed—as in the Almighty’s saying: "So remind by the Quran whoever fears My threat," and His saying: "So turn away from whoever turns his back on Our remembrance." His knowledge, may Allah exalt him and grant him peace, of those whose hearts were sealed came through Allah’s informing him of it. Therefore, after the delivery [of the message] and the establishment of the proof, he is not obligated to repeat the reminder to those he knows to have had their hearts sealed. The condition, according to this view, is literal.

It is also said that it is not so, and that it is merely an exclusion of benefit with respect to those mentioned, rebuking them for their persistence; as if it were said: Do what you have been commanded so that you may be rewarded, even if they do not benefit from it. In this is consolation for him, may Allah exalt him and grant him peace. The first view is preferred because it maintains the condition in its literal sense while being more appropriate to His saying: [The rest of the verse].