Translation (Maududi)
"Thus, (it is a fact that) whomsoever Allah wills to guide, He opens his breast for Islam; and whomsoever He wills to let go astray, He causes his breast to become strait and constricted, as if he were climbing towards the sky. Thus Allah lays the abomination on those who do not believe."
One of the most psychologically penetrating verses in the Qur'an. The internal experience of guidance is described as sharḥ al-ṣadr — the opening, the expansion, the spaciousness of the chest. Islam becomes natural, light, capacious; the believer breathes freely. The opposite — willful misguidance — is described as ḍayyiq ḥaraj: a tight, constricted, suffocating chest, "as if he were climbing into the sky" (the higher one ascends, the thinner the air, the harder to breathe). Maududi explains: this is not just metaphor; many former disbelievers, on accepting Islam, have testified to a literal sensation of physical and spiritual relief — and many obstinate rejecters live with a chronic inner constriction they cannot name.