Quran 7:203 from Surah Al-A'raaf on Divine Marvels.
وَإِذَا لَمۡ تَأۡتِهِم بِـَٔايَةٖ قَالُواْ لَوۡلَا ٱجۡتَبَيۡتَهَاۚ قُلۡ إِنَّمَآ أَتَّبِعُ مَا يُوحَىٰٓ إِلَيَّ مِن رَّبِّيۚ هَٰذَا بَصَآئِرُ مِن رَّبِّكُمۡ وَهُدٗى وَرَحۡمَةٞ لِّقَوۡمٖ يُؤۡمِنُونَ
English translation: And when not you bring them a Sign they say Why (have) not you devised it Say Only I follow what is revealed to me from my Lord This (is) enlightenment from your Lord and guidance and mercy for a people who believe
Transliteration: wa-idha lam tatihim biayatin qalu lawla ij'tabaytaha qul innama attabi'u ma yuha ilayya min rabbi hadha basairu min rabbikum wahudan warahmatun liqawmin yu'minuna