Surah Ali'Imran, Verse 20

فَإِنۡ حَآجُّوكَ فَقُلۡ أَسۡلَمۡتُ وَجۡهِيَ لِلَّهِ وَمَنِ ٱتَّبَعَنِۗ وَقُل لِّلَّذِينَ أُوتُواْ ٱلۡكِتَٰبَ وَٱلۡأُمِّيِّـۧنَ ءَأَسۡلَمۡتُمۡۚ فَإِنۡ أَسۡلَمُواْ فَقَدِ ٱهۡتَدَواْۖ وَّإِن تَوَلَّوۡاْ فَإِنَّمَا عَلَيۡكَ ٱلۡبَلَٰغُۗ وَٱللَّهُ بَصِيرُۢ بِٱلۡعِبَادِ٢٠

fa-in ḥājjūka faqul aslamtu wajhiya lillahi wamani ittabaʿani waqul lilladhīna ūtū l-kitāba wal-umiyīna a-aslamtum fa-in aslamū faqadi ih'tadaw wa-in tawallaw fa-innamā ʿalayka l-balāghu wal-lahu baṣīrun bil-ʿibādi

So if they argue with you, say, "I have submitted myself to Allāh [in Islām], and [so have] those who follow me." And say to those who were given the Scripture and [to] the unlearned, "Have you submitted yourselves?" And if they submit [in Islām], they are rightly guided; but if they turn away - then upon you is only the [duty of] notification. And Allāh is Seeing of [His] servants.