Surah 3. Aal-Imran, Ayah 178

This is an allusion to the doctrine of natural law (in Qur'anic terminology, sunnat Allah, "God's way") to which man's inclinations and actions - as well as all other happenings in the universe - are subject. The above verse says, as it were, "Since these people are bent on denying the truth, Our giving them rein [that is, freedom of choice and time for a reconsideration of their attitude] will not work out for their benefit but will, on the contrary, cause them to grow in false self-confidence and, thus, in sinfulness." As in many similar passages in the Qur'an, God attributes here their "growing in sinfulness" to His own will because it is He who has imposed on all His creation the natural law of cause and effect. (See also note [4] on 14:4 .)

That the cup of their iniquity may be full. The appetite for sin grows with what it feeds on. The natural result is that the sinner sinks deeper into sin. If there is any freedom of will, this naturally follows, though Allah's Grace is always ready for the repentant. If the Grace is rejected, the increase of iniquity makes the nature of iniquity plainer to those who might otherwise be attracted by its glitter. The working of Allah's Law is therefore both just and merciful. See also the next verse.