The Messenger of Allah ﷺ said, "Nothing of a human being remains uncorrupted except a single bone, the coccyx, and from it the creation will be reassembled on the Day of Resurrection."
حدثنا أبو بكر بن أبي شيبة حدثنا أبو معاوية عن الأعمش عن أبي صالح
قال رسول الله ﷺ ليس شيء من الإنسان إلا يبلى إلا عظما واحدا وهو عجب الذنب ومنه يركب الخلق يوم القيامة
Bukhari narrated it in the Book of Tafsir, chapter, "The day the trumpet is blown and you come forth in droves," hadith no. 4935, and Muslim narrated it in the Book of Fitan, chapter, "What is between the two blowings of the trumpet," hadith no. 2955/141, from the hadith of Abu Muawiya, in a longer form.