"And your people have denied it, while it is the truth," meaning: the Quran. "Say: I am not a manager over you," meaning: a guardian over your deeds so that I may reward you for them. I am only a warner, and Allah is the One who will reward you for your deeds.
﴿وَكَذَّبَ بِهِ قَوْمُكَ وَهُوَ الْحَقُّ﴾ يَعْنِي: الْقُرْآنَ ﴿قُلْ لَسْتُ عَلَيْكُمْ بوكيل﴾ بِحَفِيظٍ لِأَعْمَالِكُمْ حَتَّى [أُجَازِيَكُمْ] بِهَا إِنَّمَا أَنَا مُنْذِرٌ، وَاللَّهُ الْمُجَازِي لكم بأعمالكم.