Quran 4:49 An-Nisa, ayah 49 of 176

أَلَمْ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُم ۚ بَلِ ٱللَّهُ يُزَكِّى مَن يَشَآءُ وَلَا يُظْلَمُونَ فَتِيلًا ۝٤٩

4:49 Hast thou not seen those who praise themselves for purity? Nay, Allah purifieth whom He will, and they will not be wronged even the hair upon a date-stone.