Quranic authenticity and miracle

ذَٰلِكَ مِنْ أَنۢبَآءِ ٱلْغَيْبِ نُوحِيهِ إِلَيْكَ ۖ وَمَا كُنتَ لَدَيْهِمْ إِذْ أَجْمَعُوٓا۟ أَمْرَهُمْ وَهُمْ يَمْكُرُونَ

That is from the news of the unseen which We reveal, [O Muḥammad], to you. And you were not with them when they put together their plan while they conspired.