﴿ فَمَن يُرِدِ ٱللَّهُ أَن يَهْدِيَهُۥ يَشْرَحْ صَدْرَهُۥ لِلْإِسْلَٰمِ ۖ وَمَن يُرِدْ أَن يُضِلَّهُۥ يَجْعَلْ صَدْرَهُۥ ضَيِّقًا حَرَجًۭا كَأَنَّمَا يَصَّعَّدُ فِى ٱلسَّمَآءِ ۚ كَذَٰلِكَ يَجْعَلُ ٱللَّهُ ٱلرِّجْسَ عَلَى ٱلَّذِينَ لَا يُؤْمِنُونَ ﴾

“And whomsoever God wills to guide, his bosom He opens wide with willingness towards self-surrender [unto Him]; and whomsoever He wills to let go astray, his bosom He causes to be tight and constricted, as if he were climbing unto the skies: it is thus that God inflicts horror upon those who will not believe.”

(And whomsoever it is Allah's will to guide) to His religion, (He expandeth his bosom) His heart (unto the Surrender) unto accepting Islam, (and whomsoever it is His will to send astray) to leave in error and disbelief, (He maketh his bosom) He leaves his heart (close) like the ferrule of a spear (and narrow) in doubt; this could also mean: the light cannot find a way, or a passage to his heart (as if he were engaged in sheer ascent) like a person who is told to rise in heaven: the heart of such a person is not guided to Islam. (Thus Allah layeth ignominy) Allah leaves denial (upon those) in the heart of those (who believe not) in Muhammad (pbuh), or in the Qur'an, and then He punishes them for their disbelief.