Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:47:24 –

Then do they not reflect upon the Qur'an, or are there locks upon ˹their˺ hearts?  

Do they not contemplate the Qur’ān?, and so recognise the truth. Or (am here is like bal, ‘nay, but’) is it that there are locks on, their, hearts?, so they are unable to comprehend it.
القرآن:٤٧:٢٤ –

أَفَلَا يَتَدَبَّرُونَ الْقُرْآنَ أَمْ عَلَىٰ قُلُوبٍ أَقْفَالُهَا  

{أفلا يتدبرون القرآن} فيعرفون الحق {أم} بل {على قلوب} لهم {أقفالها} فلا يفهمونه.