Surah Al-Qasas, ayah 53

28:53

وَإِذَا يُتۡلَىٰ عَلَيۡهِمۡ قَالُوٓاْ ءَامَنَّا بِهِۦٓ إِنَّهُ ٱلۡحَقُّ مِن رَّبِّنَآ إِنَّا كُنَّا مِن قَبۡلِهِۦ مُسۡلِمِينَ ٥٣

Wa idhā yutlā 'alayhim qālū āmannā bihī innahul-haqqu mir rabbinā innā kunnā min qablihī muslimīn

And when it is recited to them, they say, "We have believed in it; indeed, it is the truth from our Lord. Indeed we were, [even] before it, Muslims [i.e., submitting to Allāh]."