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

Have you not considered those who attribute purity to themselves? Nay, Allah purifies whom He pleases; and they shall not be wronged the husk of a date stone.