The limitation of prophetic authority to conveying the message

بَقِيَّتُ ٱللَّهِ خَيْرٌ لَّكُمْ إِن كُنتُم مُّؤْمِنِينَ ۚ وَمَآ أَنَا۠ عَلَيْكُم بِحَفِيظٍ

What remains [lawful] from Allāh is best for you, if you would be believers. But I am not a guardian over you."