Hadith on Jahannam: Hellfire seventy times stronger than earthly fire

Abu Huraira reported: The Prophet, peace and blessings be upon him, said, “Your fire, which the son of Adam ignites, is only one of seventy parts from the fire of Hell.” They said, “By Allah, that would be enough, O Messenger of Allah!” The Prophet said, “Verily, it exceeds it by sixty nine parts, each of which are like its heat.

Source: Ṣaḥīḥ Muslim 2843

Grade: Sahih (authentic agreed upon) according to Muslim

عَنْ أَبِي هُرَيْرَةَ أَنَّ النَّبِيَّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ نَارُكُمْ هَذِهِ الَّتِي يُوقِدُ ابْنُ آدَمَ جُزْءٌ مِنْ سَبْعِينَ جُزْءًا مِنْ حَرِّ جَهَنَّمَ قَالُوا وَاللهِ إِنْ كَانَتْ لَكَافِيَةً يَا رَسُولَ اللهِ قَالَ فَإِنَّهَا فُضِّلَتْ عَلَيْهَا بِتِسْعَةٍ وَسِتِّينَ جُزْءًا كُلُّهَا مِثْلُ حَرِّهَا

2843 صحيح مسلم كتاب الجنة وصفة نعيمها وأهلها باب في شدة حر نار جهنم وبعد قعرها وما تأخذ من المعذبين