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].
The Saheeh International Quran Translation
أَلَمْ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُم بَلِ ٱللَّهُ يُزَكِّى مَن يَشَآءُ وَلَا يُظْلَمُونَ فَتِيلًاHave 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].