Even the Prophet does not have the Duty of Guiding People to the Right Path or Saving them from Punishment.
Is, then one against whom the Word of punishment justified (equal to the one who avoids evil).
Will you (Prophet) rescue him who is in the Fire?
Verily, you can't not guide aright everyone whom you lovest: but it is God who guides him that wills [to be guided]; and He is fully aware of all who would let themselves be guided.
The point in the following verse is that people should seek guidance with their own free will. Even if the person warning is a prophet, they cannot guide the recipient unless they want it. The important thing is to convey the message. Despite this, those who fail to follow the right path are responsible for it. Almighty Allah informs us that guidance will not be shaped according to the will of the Prophet Muhammad, but that whoever seeks it will be guided.
Not upon you (Muhammad) is their guidance, but Allah guides whom He wills. And whatever you spend in good, it is for yourselves, when you spend not except seeking Allah's Countenance. And whatever you spend in good, it will be repaid to you in full, and you shall not be wronged.
The following verse states that Prophet Muhammad is not responsible for the lack of purification of Allah's servants. People should not even ask those to whom they give charity or alms to be guided. Because the true determining factor in guidance is a person's own will. Guidance is a matter of intellect, will, and heart. A person must seek guidance for themselves so that Allah Almighty can create it for him.
though you are not liable if he does not purify himself. (from disbelief, you are only a Messenger, your duty is to convey the Message of Allah).
In the verse below, we should note that the Prophet Muhammad's duty in terms of guidance is "to show the right way(Quran)."
52.And thus We have sent to you (Muhammad) Ruhan (an Inspiration, and a Mercy) of Our Command.
You knew not what is the Book, nor what is Faith.
But We have made it (this Quran) a light wherewith We guide whosoever of Our slaves We will.
And verily, you (Muhammad) are indeed guiding (mankind) to the Straight Path.
53. The Path of Allah, to Whom belongs all that is in the heavens and all that is in the earth. Verily, all the matters at the end go to Allah (for decision).
Now if they turn away, We have not sent you as their keeper: your responsibility is only to convey the message. Man is such that when We let him taste Our mercy, he exults(rejoices) in it, but if an evil befalls(happen to) him which is his own doing, he becomes utterly ungrateful.
Had Allah willed, they would not have taken others besides Him in worship.
And We have not made you a watcher over them nor are you set over them to dispose of their affairs.
Verily, proofs have come to you from your Lord, so whosoever sees, will do so for (the good of) his ownself, and whosoever blinds himself, will do so to his own harm, and I (Muhammad) am not a watcher over you.
Indeed guidance rests with Us,
And upon Allah is the direction of the [right] way, and among the various paths are those deviating. And if He willed, He could have guided you all.