Indeed, the most beloved of Ali's names to him was Abu Turab, and he would rejoice when called by it. No one named him Abu Turab except the Prophet ﷺ.One day Ali became upset with Fatimah, so he went out and lay down against the wall by the mosque. The Prophet ﷺ came looking for him, and someone said, "There he is, lying against the wall."The Prophet ﷺ came to him, and his back had become covered in dust. The Prophet ﷺ began wiping the dust from his back, saying, "Sit up, Abu Turab."
إن كانت أحب أسماء علي إليه لأبو تراب، وإن كان ليفرح أن يدعى بها، وما سماه أبو تراب إلا النبي ﷺ غاضب يوما فاطمة فخرج، فاضطجع إلى الجدار إلى المسجد، فجاءه النبي ﷺ يتبعه، فقال: هو ذا مضطجع في الجدار، فجاءه النبي ﷺ وامتلأ ظهره ترابا، فجعل النبي ﷺ يمسح التراب عن ظهره ويقول: اجلس يا أبا تراب.
Bukhari narrated it in Al-Adab (6204) and Muslim in Fadail al-Sahabah (2409), both through Abu Hazim, from Sahl bin Saad, who related it. The wording given is Bukhari's, and Muslim's wording is similar, with a story at its beginning.