Jami` at-Tirmidhi Book 10, Hadith 60
from his father who said: "When the Messenger of Allah would perform the Salat for the funeral he would said: (Allahammaghfir li-hayyina wa mayyittina, wa shahidina wa gha'ibina, wa saghirina wa kabirina, wa dhakarina wa unthana) 'O Allah! Forgive our living and our deceased, our present and our absent, our young and our old, our male and our female.'"
"Zaid bin Arqam would say four Takbir for our funerals. (Once) he said five Takbir for a funeral so we asked him about that and he said: 'The Messenger of Allah would say those Takbir.'"
"I heard the Messenger of Allah, while he was performing Salat for a deceased person. I could hear him saying in his prayer: (Allahummagfir lahu, war hamhu, waghsilhu bil-baradi (waghsilhu) kama yughsaluth-thawb) 'O Allah! Forgive him, have mercy upon him, and wash him with (snow or ice) (and wash him) just as a garment is washed.'"