Surah Az-Zukhruf 43:81

قُلْ إِن كَانَ لِلرَّحْمَـٰنِ وَلَدٌ فَأَنَا۠ أَوَّلُ ٱلْعَـٰبِدِينَ

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

Translation: Saheeh International

Tafsir

Say ‘If the Compassionate One had a son hypothetically speaking I would have been first among the worshippers of that son; but it is established that He exalted be He does not have a child and thus there can be no worshipping of such a child.

Excerpt from Tafsir al-Jalalayn, commentary on 43:81, via Quran.com. The reader has the full commentary and 9 more tafsirs.