Sahl ibn Ziyad, from al-Hasan ibn Ali, from Muhammad ibn al-Fudayl, from Ishaq ibn Ammar, from Abu Abdillah عليه السلام, who said:
Imam عليه السلام said: "The first gift given to a believer (who has died) is that forgiveness is granted to those who follow his funeral procession."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 483