Quran 6:125 from Surah Al-An'aam on Divine Marvels.
فَمَن يُرِدِ ٱللَّهُ أَن يَهۡدِيَهُۥ يَشۡرَحۡ صَدۡرَهُۥ لِلۡإِسۡلَٰمِۖ وَمَن يُرِدۡ أَن يُضِلَّهُۥ يَجۡعَلۡ صَدۡرَهُۥ ضَيِّقًا حَرَجٗا كَأَنَّمَا يَصَّعَّدُ فِي ٱلسَّمَآءِۚ كَذَٰلِكَ يَجۡعَلُ ٱللَّهُ ٱلرِّجۡسَ عَلَى ٱلَّذِينَ لَا يُؤۡمِنُونَ
English translation: So whoever wants Allah that He guides him He expands his breast to Islam and whoever He wants that He lets him go astray He makes his breast tight and constricted as though he (were) climbing into the sky Thus places Allah the filth on those who (do) not believe
Transliteration: faman yuridi al-lahu an yahdiyahu yashrah sadrahu lil'is'lami waman yurid an yudillahu yaj'al sadrahu dayyiqan harajan ka-annama yassa'adu fi al-samai kadhalika yaj'alu al-lahu al-rij'sa ala alladhina la yu'minuna