Sa’ad from Ya'qub ibn Yazid from Ibn Abi 'Umayr from Hisham ibn Salim from Abu Abdillah عليه السلام, peace be upon him, who said:
Imam al-Sadiq عليه السلام said: “There is no harm if a man performs the prayer over the deceased (Salat Al Mayyit), after he has been buried.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 221