Surah An-Nisaa, Verse 49
أَلَمْ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُم ۚ بَلِ ٱللَّهُ يُزَكِّى مَن يَشَآءُ وَلَا يُظْلَمُونَ فَتِيلًا
Translation — Sahih International
Have you not seen those who claim themselves to be pure? Rather, Allah purifies whom He wills, and injustice is not done to them, [even] as much as a thread [inside a date seed].
Source
Kur'an-ı Kerim, Nisâ Suresi 4:49
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/4-suresi-49-ayet