Surah Al-Anfal 8:55

إِنَّ شَرَّ ٱلدَّوَآبِّ عِندَ ٱللَّهِ ٱلَّذِينَ كَفَرُوا۟ فَهُمْ لَا يُؤْمِنُونَ

Indeed, the worst of living creatures in the sight of Allāh are those who have disbelieved, and they will not [ever] believe-

Translation: Saheeh International

Tafsir

The following was revealed regarding Banū Qurayza Surely the worst of beasts in God’s sight are the ungrateful who will not believe

Excerpt from Tafsir al-Jalalayn, commentary on 8:55, via Quran.com. The reader has the full commentary and 9 more tafsirs.