Surah Al-An'am, ayah 19

قُلۡ أَيُّ شَيۡءٍ أَكۡبَرُ شَهَٰدَةٗۖ قُلِ ٱللَّهُۖ شَهِيدُۢ بَيۡنِي وَبَيۡنَكُمۡۚ وَأُوحِيَ إِلَيَّ هَٰذَا ٱلۡقُرۡءَانُ لِأُنذِرَكُم بِهِۦ وَمَنۢ بَلَغَۚ أَئِنَّكُمۡ لَتَشۡهَدُونَ أَنَّ مَعَ ٱللَّهِ ءَالِهَةً أُخۡرَىٰۚ قُل لَّآ أَشۡهَدُۚ قُلۡ إِنَّمَا هُوَ إِلَٰهٞ وَٰحِدٞ وَإِنَّنِي بَرِيٓءٞ مِّمَّا تُشۡرِكُونَ ١٩

Qul ayyu shay'in akbaru shahādatan qulillāhu shahīdu baynī wabaynakum wa ūhiya ilayya hādhal-qur'ānu li undhirakum bihī wamam balagha a'innakum latashhadūna anna ma'allāhi ālihatan ukhrā qul lā ashhadu qul innamā huwa ilāhun wāhidun wa innanī barī'um mimmā tushrikūn

Say, "What thing is greatest in testimony?" Say, "Allāh is witness between me and you. And this Qur’ān was revealed to me that I may warn you thereby and whomever it reaches.²⁹⁸ Do you [truly] testify that with Allāh 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]."