Abdullah ibn al-Salt from al-Hasan ibn Mahbub from Abu Walad who said:
I asked Abu Abdillah عليه السلام, peace be upon him, about the takbirs over the deceased. Imam عليه السلام said: “Five (takbirs).”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 349