(Az-Zukhuruf) 43 : 81
قُلْ إِنْ كَانَ لِلرَّحْمَٰنِ وَلَدٌ فَأَنَا أَوَّلُ الْعَابِدِينَ

You say: If the Impartial had a son, then I would have been the first among those who are serving Him.

See explanation 19: 94-95; and 42: 11-14, 44.