Surah Adh-Dhariyat 51:39

فَتَوَلَّىٰ بِرُكْنِهِۦ وَقَالَ سَـٰحِرٌ أَوْ مَجْنُونٌ

But he turned away with his supporters and said, "A magician or a madman."

Translation: Saheeh International

Tafsir

but he turned away he rejected belief to his supports bi-ruknihi his hosts so called because to him they are like a support rukn saying to Moses that he Moses was ‘A sorcerer or a madman!’

Excerpt from Tafsir al-Jalalayn, commentary on 51:39, via Quran.com. The reader has the full commentary and 9 more tafsirs.