Surah Ash-Shu'ara 26:20

قَالَ فَعَلْتُهَآ إِذًا وَأَنَا۠ مِنَ ٱلضَّآلِّينَ

[Moses] said, "I did it, then, while I was of those astray [i.e., ignorant].

Translation: Saheeh International

Tafsir

He Moses said ‘I did that then when I was astray from the knowledge and the Message which God would later give me.

Excerpt from Tafsir al-Jalalayn, commentary on 26:20, via Quran.com. The reader has the full commentary and 9 more tafsirs.