In the fourth verse (106), the Holy Prophet ﷺ at has been guided to a specific course of action. He has been asked not to worry about the acceptance or non-acceptance of the call. For him, the best course was to keep following the way revealed to him through Wahy from his Rabb, the major element of which is the belief that no one is worthy of worship but Allah. That he should continue preaching with his message of truth is part of what has been revealed. So, believing in Allah and remaining steadfast on the way ordained for him, he should avoid feeling concerned about disbelievers and their unfortunate non-acceptance of the call.
Allah commands His Messenger and those who followed his path,
(Follow what has been inspired to you from your Lord,) meaning, follow it, obey it and act according to it. What has been revealed to you from your Lord is the Truth, no doubt, and there is no deity worthy of worship except Him,
(and turn aside from the idolators) meaning, forgive them, be forbearing and endure their harm until Allah brings relief to you, supports you and makes you triumphant over them. Know -- O Muhammad -- that there is a wisdom behind misleading the idolators, and that had Allah willed, He would have directed all people to guidance,
(Had Allah willed, they would not have taken others besides Him in worship.) Allah's is the perfect will and wisdom in all decrees and decisions, and He is never questioned about what He does, while they all will be questioned. Allah's statement,
(And We have not made you Hafiz over them.) means, a watcher who observes their statements and deeds,
(Nor are you set over them to dispose of their affairs. ) or to control their provision. Rather, your only job is to convey, just as Allah said,
(So remind them, you are only one who reminds. You are not a dictator over them.) 88:21-22 and,
(Your duty is only to convey and on Us is the reckoning.) 13:40