Quran 28:53 from Surah Al-Qasas on Divine Marvels.
وَإِذَا يُتۡلَىٰ عَلَيۡهِمۡ قَالُوٓاْ ءَامَنَّا بِهِۦٓ إِنَّهُ ٱلۡحَقُّ مِن رَّبِّنَآ إِنَّا كُنَّا مِن قَبۡلِهِۦ مُسۡلِمِينَ
English translation: And when it is recited to them they say We believe in it Indeed, it (is) the truth from our Lord Indeed, we [we] were before it before it Muslims
Transliteration: wa-idha yut'la alayhim qalu amanna bihi innahu al-haqu min rabbina inna kunna min qablihi mus'limina