Surah Al-A'raf, ayah 21

وَقَاسَمَهُمَآ إِنِّي لَكُمَا لَمِنَ ٱلنَّٰصِحِينَ ٢١

Waqāsamahumā innī lakumā laminan-nāsihīn

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