Qur'an 16:89

وَيَوْمَ نَبْعَثُ فِى كُلِّ أُمَّةٍ شَهِيدًا عَلَيْهِم مِّنْ أَنفُسِهِمْ ۖ وَجِئْنَا بِكَ شَهِيدًا عَلَىٰ هَـٰٓؤُلَآءِ ۚ وَنَزَّلْنَا عَلَيْكَ ٱلْكِتَـٰبَ تِبْيَـٰنًا لِّكُلِّ شَىْءٍ وَهُدًى وَرَحْمَةً وَبُشْرَىٰ لِلْمُسْلِمِينَ

And (bethink you of) the day when We raise in every nation a witness against them of their own folk, and We bring thee (Muhammad) as a witness against these. And We reveal the Scripture unto thee as an exposition of all things, and a guidance and a mercy and good tidings for those who have surrendered (to Allah).