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:18:98 –

˹Dhul-Qarnayn˺ said, "This is a mercy from my Lord; but when the promise of my Lord comes, He will make it level, and ever is the promise of my Lord true."  

Said he, Dhū’l-Qarnayn, ‘This, namely, the barrier, the ability to make it, is a mercy from my Lord, a grace ˹from Him˺, because it prevents them from coming forth. But when the promise of my Lord comes to pass, ˹the promise˺ of their coming forth, which will be near ˹the time of˺ the Resurrection, He will level it, pulverised and flattened, for my Lord’s promise, of their coming forth and ˹of˺ other things, is ˹always˺ true’, it will be. God, exalted be He says:
القرآن:١٨:٩٨ –

قَالَ هَٰذَا رَحْمَةٌ مِنْ رَبِّي ۖ فَإِذَا جَاءَ وَعْدُ رَبِّي جَعَلَهُ دَكَّاءَ ۖ وَكَانَ وَعْدُ رَبِّي حَقًّا  

{قال} ذو القرنين {هذا} أي السد، أي الإقدار عليه {رحمة من ربي} نعمة لأنه مانع من خروجهم {فإذا جاء وعد ربي} بخروجهم القريب من البعث {جعله دكاء} مدكوكا مبسوطا {وكان وعد ربي} بخروجهم وغيره {حقا} كائنا قال تعالى: