"And the day We will raise among every nation a witness over them from themselves," meaning: their Prophet; he is a witness over them. "And We brought you, [O Muhammad], as a witness over these," meaning: his nation. "And We have sent down to you the Book as clarification for all things," meaning: what He has clarified therein of the lawful and the unlawful, and everything that Allah has revealed within it.
Surah An-Nahl, from verse (90) to verse (92).
﴿وَيَوْمَ نَبْعَثُ فِي كُلِّ أُمَّةٍ شَهِيدا عَلَيْهِم من أنفسهم﴾ يَعْنِي: نَبِيَّهُمْ؛ هُوَ شَاهِدٌ عَلَيْهِمْ ﴿وَجِئْنَا بك﴾ يَا مُحَمَّدُ ﴿شَهِيدًا عَلَى هَؤُلاءِ﴾ يَعْنِي: أُمَّتَهُ ﴿وَنَزَّلْنَا عَلَيْكَ الْكِتَابَ تبياناً لكل شيءٍ﴾ يَعْنِي: مَا بَيَّنَ فِيهِ مِنَ الْحَلالِ وَالْحَرَامِ، وَكُلِّ مَا أَنْزَلَ الله فِيهِ.
سُورَة النَّحْل من الْآيَة (٩٠) إِلَى الْآيَة (٩٢).