“That God may purify those who believe,” meaning: He tests them, according to the interpretation of Mujahid. “And destroy the disbelievers,” meaning: He will destroy their deeds on the Day of Resurrection.

Muhammad said: It is also said that the meaning of “That God may purify” is: He purifies their sins. The root meaning of purification (at-tamhis) is: cleansing and purging.