Answer:
First, it should be noted that the ancient Israelite religion is different from later forms of Judaism. The Hebrews were forbidden to talk to the dead, as nomads, burial meant moving on.
The Mesopotamians believed that there was an underworld and one's status in the underworld directly stemmed from how well the burial rites were performed. Those less fortunate were doomed to eat dust for all eternity, while others could sit and listen to music.