ENOfficial
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.
Source: sunnah.com
Other translations
Arabic
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
sunnah.com