[ Abdullah Yusuf Ali ]
No soul can believe, except by the will of Allah, and He will place Doubt (or obscurity) on those who will not understand.
1481 To creatures endued with Will, Faith comes out of an active use of that Will. But we must not be so arrogant as to suppose that that is enough. At best, man is weak and in need of Allah's grace and help. If we sincerely wish to understand, He will help our Faith; but if not, our doubts and difficulties will only be increased. This follows as a necessary consequence, and in Qur'anic language all consequences are ascribed to Allah, the Cause of Causes.
1482 Rijs (from rajisa, yarjisu, or rajasa, yarjasu) has various meanings: e.g., (1) filth, impurity, uncleanness, abomination, as in 9:95; (2) hence, filthy deeds, foul conduct, crime, abomination, thus shading off into (1), as in 5:90; (3) hence punishment for crime, penalty, as in 6:125; (4) a form of such punishment, viz., doubt, obscurity, or unsettlement of mind, anger, indignation, as in 9:125, and here, but perhaps the idea of punishment is also implied here.