Sahih Muslim , Book 54, Hadith 179 (In-Book) ⓘ

Abu Huraira reported so many ahadith from Allah's Apostle and amongst these one was this that Allah's Messenger said: There is a bone in the human being which the earth would never consume and it is from this that new bodies would be reconstituted (on the Day of Resurrection). They said: Allah's Messenger, which bone is that? Thereupon he said: It is the spinal bone.

حَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، قَالَ هَذَا مَا حَدَّثَنَا أَبُو هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فَذَكَرَ أَحَادِيثَ مِنْهَا وَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِنَّ فِي الإِنْسَانِ عَظْمًا لاَ تَأْكُلُهُ الأَرْضُ أَبَدًا فِيهِ يُرَكَّبُ يَوْمَ الْقِيَامَةِ ‏"‏ ‏.‏ قَالُوا أَىُّ عَظْمٍ هُوَ يَا رَسُولَ اللَّهِ قَالَ ‏"‏ عَجْبُ الذَّنَبِ ‏"‏ ‏.‏