It was narrated from Abu Sa’eed Al-Khudri that the Prophet (ﷺ) said: “The disbeliever will be made huge so much so that his molar will be bigger than (Mount) Uhud, and the size of his body in relation to his molar will be like the size of the body of anyone of you in relation to his molar.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا بَكْرُ بْنُ عَبْدِ الرَّحْمَنِ، حَدَّثَنَا عِيسَى بْنُ الْمُخْتَارِ، عَنْ مُحَمَّدِ بْنِ أَبِي لَيْلَى، عَنْ عَطِيَّةَ الْعَوْفِيِّ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ " إِنَّ الْكَافِرَ لَيَعْظُمُ حَتَّى إِنَّ ضِرْسَهُ لأَعْظَمُ مِنْ أُحُدٍ وَفَضِيلَةُ جَسَدِهِ عَلَى ضِرْسِهِ كَفَضِيلَةِ جَسَدِ أَحَدِكُمْ عَلَى ضِرْسِهِ " .
sunnah.com