Surah Al-A'raf 7:21

وَقَاسَمَهُمَآ إِنِّى لَكُمَا لَمِنَ ٱلنَّـٰصِحِينَ

And he swore [by Allāh] to them, "Indeed, I am to you from among the sincere advisors."

Translation: Saheeh International

Tafsir

And he swore to both of them that is he swore to both of them by God ‘Truly I am a sincere adviser to you’ in this matter.

Excerpt from Tafsir al-Jalalayn, commentary on 7:21, via Quran.com. The reader has the full commentary and 9 more tafsirs.