Quran 80:3 from Surah Abasa on Divine Marvels.
وَمَا يُدۡرِيكَ لَعَلَّهُۥ يَزَّكَّىٰٓ
English translation: But what would make you know that he might purify himself
Transliteration: wama yud'rika la'allahu yazzakka