Surah Az-Zukhruf, Verse 81

قُلۡ إِن كَانَ لِلرَّحۡمَٰنِ وَلَدٞ فَأَنَا۠ أَوَّلُ ٱلۡعَٰبِدِينَ٨١

qul in kāna lilrraḥmāni waladun fa-anā awwalu l-ʿābidīna

Say, [O Muḥammad], "If the Most Merciful had a son, then I would be the first of [his] worshippers."