"Indeed, your Lord is most knowing of who strays from His way, and He is most knowing of the [rightly] guided." He knows that Muhammad is upon guidance, and that the polytheists have strayed from His way.
Surat al-An'am from verse (118) to verse (121).
﴿إِنَّ رَبَّكَ هُوَ أَعْلَمُ مَنْ يَضِلُّ عَنْ سَبِيلِهِ وَهُوَ أَعْلَمُ بالمهتدين﴾ فَهُوَ يَعْلَمُ أَنَّ مُحَمَّدًا عَلَى الْهُدَى، وَأَنَّ الْمُشْرِكِينَ ضَلُّوا عَنْ سَبيله.
سُورَة الْأَنْعَام من الْآيَة (١١٨) إِلَى الْآيَة (١٢١).