From him, from Abu Abdillah عليه السلام:
Imam عليه السلام said: "The Prophet صلى الله عليه وعلى آله وسلم, prohibited adding soil to the grave that was not taken out from it."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 488