The Messenger of Allah ﷺ said, "Every son of Adam," and in the narration of Mughirah, "Every child of Adam will be consumed by the earth except the tailbone. From it he was created, and from it he will be reassembled."
أخبرنا قتيبة عن مالك ومغيرة عن أبي الزناد عن الأعرج
قال رسول الله ﷺ كل بني آدم وفي حديث مغيرة كل ابن آدم يأكله التراب إلا عجب الذنب منه خلق وفيه يركب
Muslim narrated it, in the chapter on the period between the two blasts of the trumpet, hadith: 142/2955, from Qutayba, from Mughira, with this wording. It is also found in Kubra, hadith: 2204, and in Muwatta (Yahya): 239/1.