(28) Events of the Day of Resurrection and the Beginning of Creation
كتاب أحوال القيامة وبدء الخلق
(7b) Chapter: Description of Hell and its Inhabitants - Section 2
(7) باب صفة النار وأهلها - الفصل الثاني
Mishkat al-Masabih 5675 
He reported God's messenger as saying, "The thickness of an infidel's skin will be forty-two cubits, his molar tooth will be like Uhud, and his seat in Jahannam will be like the distance between Mecca and Medina." Tirmidhi transmitted it.
وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِنَّ غِلَظَ جِلْدِ الْكَافِرِ اثْنَانِ وَأَرْبَعُونَ ذِرَاعًا وَإِنَّ ضِرْسَهُ مِثْلُ أُحُدٍ وَإِنَّ مَجْلِسَهُ مِنْ جَهَنَّمَ مَا بَيْنَ مَكَّةَ وَالْمَدِينَةِ» . رَوَاهُ التِّرْمِذِيّ
Reference : Mishkat al-Masabih 5675
In-book reference : Book 28, Hadith 146