فَإِن تَوَلَّوْا۟ فَقَدْ أَبْلَغْتُكُم مَّآ أُرْسِلْتُ بِهِۦٓ إِلَيْكُمْ وَيَسْتَخْلِفُ رَبِّى قَوْمًا غَيْرَكُمْ وَلَا تَضُرُّونَهُۥ شَيْـًٔا إِنَّ رَبِّى عَلَىٰ كُلِّ شَىْءٍ حَفِيظٌ ٥٧
But if you turn away, then I have already conveyed that with which I was sent to you. My Lord will give succession to a people other than you, and you will not harm Him at all. Indeed my Lord is, over all things, Guardian."
Explanation: Al-Mukhtasar
He told them that if they continued to turn away from what he brought them, then he had no responsibility to do more than convey the message to them. He had delivered to them everything that Allah had sent him with and instructed him to convey. The proof would be against them, and his Lord would destroy them and bring another people to succeed them. They would not do Allah the slightest harm through their rejecting and turning away, because He has no need of His creation. He told them that his Lord watches over all things, and that it was He Who protected him from the evil they plotted against him.