Surah An-Nisa 4:49

أَلَمْ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُم ۚ بَلِ ٱللَّهُ يُزَكِّى مَن يَشَآءُ وَلَا يُظْلَمُونَ فَتِيلًا

Have you not seen those who claim themselves to be pure? Rather, Allāh purifies whom He wills, and injustice is not done to them, [even] as much as a thread [inside a date seed].

Translation: Saheeh International

Tafsir

Have you not seen those who praise themselves for purity? namely the Jews when they say ‘We are God’s children and His beloved’ in other words it is not a matter of their purifying themselves. …

Excerpt from Tafsir al-Jalalayn, commentary on 4:49, via Quran.com. The reader has the full commentary and 9 more tafsirs.