Sura 6: Verse19

قُلْ أَىُّ شَىْءٍ أَكْبَرُ شَهَٰدَةًۖ قُلِ ٱللَّهُۖ شَهِيدٌۢ بَيْنِى وَبَيْنَكُمْۚ وَأُوحِىَ إِلَىَّ هَٰذَا ٱلْقُرْءَانُ لِأُنذِرَكُم بِهِۦ وَمَنۢ بَلَغَۚ أَئِنَّكُمْ لَتَشْهَدُونَ أَنَّ مَعَ ٱللَّهِ ءَالِهَةً أُخْرَىٰۚ قُل لَّآ أَشْهَدُۚ قُلْ إِنَّمَا هُوَ إِلَٰهٌ وَٰحِدٌ وَإِنَّنِى بَرِىٓءٌ مِّمَّا تُشْرِكُونَ

“What thing is greatest in testimony?” Say, “Allah is witness between me and you. And this Quran was revealed to me that I may warn you thereby and whomever it reaches. Do you [truly] testify that with Allah there are other deities?” Say, “I will not testify [with you].” Say, “Indeed, He is but one God, and indeed, I am free of what you associate [with Him].”