Surah Al-An'am (The Cattle), Verse 19

قُلْ اَیُّ شَیْءٍ اَكْبَرُ شَهَادَةً قُلِ اللّٰهُ شَهِیْدٌۢ بَیْنِیْ وَبَیْنَكُمْ وَاُوْحِیَ اِلَیَّ هٰذَا الْقُرْاٰنُ لِاُنْذِرَكُمْ بِهٖ وَمَنْ بَلَغَ اَىِٕنَّكُمْ لَتَشْهَدُوْنَ اَنَّ مَعَ اللّٰهِ اٰلِهَةً اُخْرٰی قُلْ لَّاۤ اَشْهَدُ قُلْ اِنَّمَا هُوَ اِلٰهٌ وَّاحِدٌ وَّاِنَّنِیْ بَرِیْٓءٌ مِّمَّا تُشْرِكُوْنَ ۟

Qul ayyu shai'in akbaru shahaadatan qulil laahu shaheedum bainee wa bainakum; wa oohiya ilaiya haazal Qur'aanu li unzirakum bihee wa mam balagh; a'innakum latashhadoona anna ma'al laahi aalihatan ukhraa; qul laaa ashhad; qul innamaa Huwa Ilaahunw Waahidunw wa innanee baree'um mimmaa tushrikoon

“Say: "What thing is most weighty in evidence?" Say: "Allah is witness between me and you; This Qur'an hath been revealed to me by inspiration, that I may warn you and all whom it reaches. Can ye possibly bear witness that besides Allah there is another Allah?" Say: "Nay! I cannot bear witness!" Say: "But in truth He is the one Allah, and I truly am innocent of (your blasphemy of) joining others with Him."”

Quran 6:19 (Yusuf Ali Translation)