The Truth has come (Surah Yunus 10: 108)

Say: "O people! Now the truth has come to you from your Lord. Allah, the Exalted, commands His Messenger to inform the people that that which he has brought them from Allah is the truth. It is a message concerning which there is no doubt or suspicion. Therefore, whoever is guided by it and follows it, then he only benefits himself by doing so. Likewise, whoever is misguided away from this message, then he will suffer the consequences against his own self.

And I am not set over you as a guardian;   this means, `I am not a guardian over you in order for you to become believers. I am only a warner to you and guidance belongs to Allah, the Exalted.'

Source: Tafsir ibn Kathir (Abridged)