أَلَم تَرَ إِلَى الَّذينَ يُزَكّونَ أَنفُسَهُم ۚ بَلِ اللَّهُ يُزَكّي مَن يَشاءُ وَلا يُظلَمونَ فَتيلًا

Did you see those who claim purity for themselves? Instead, God purifies whom He wills, and they won’t be wronged even by the width of a thread.