Surah Az-Zukhruf (The Ornaments of Gold), Verse 81

قُلْ اِنْ كَانَ لِلرَّحْمٰنِ وَلَدٌ فَاَنَا اَوَّلُ الْعٰبِدِیْنَ ۟

Qul in kaana lir Rahmaani walad; fa-ana awwalul 'aabideen

“Say: "If (Allah) Most Gracious had a son, I would be the first to worship."”

Quran 43:81 (Yusuf Ali Translation)