On prayer for the dead

In the life of St. Makarios of Egypt we read the following incident:

Walking one day in the desert he came across a skull. He shook it with his stick and asked. Who are you? And the skull responded by saying that I was the high priest of the idols and pagans who lived in this place. Are you the blessed Makarios, asked the skull. Know that from the moment you feel sorry for those who are in hell and pray for them, they will be released a little and find some relief.