It refers to some of them declaring others pure. Tariq ibn Shihab narrated from Ibn Masud, may Allah be pleased with him, who said: “A man may leave his home with his religion intact, then come to a man who has no power to cause him—or even himself—harm or benefit, and say, ‘By Allah, you are such-and-such!’ Then he returns home with nothing of his religion remaining.” He then recited: “Have you not seen those who claim themselves to be pure?”—the verse.

Regarding the words of the Exalted, “Rather, Allah purifies”—that is, He cleanses, absolves of sins, and sets aright—“whom He wills; and they will not be wronged even as much as a thread.” The fatil is the thread-like fibre in the cleft of a date stone. The qitmir is the thin outer membrane of the date stone, and the naqir is the tiny spot on its back. It is also said that fatil derives from twisting, referring to the bit of dirt that gathers between the fingers when they are twisted.

“See how they fabricate lies against Allah; and that alone is a manifest sin. (50) Have you not seen those who were given a portion of the Scripture? They believe in false deities and idols, and say to those who disbelieve, ‘These are better guided in their way than the believers.’ (51)”