Reference - Srimadbhagvat Puraan 5.26.10,11
(We are not human beings with spirits but we are spirits in human form - this is correct intelligence)
A person in this world, who thinks that
'This body is me'
'This wife-wealth etc is mine'
With such an intelligence, who keeps malice or Ill-will towards all living beings.
And who is continuously engaged in nurturing his own family
Such a person on leaving this body, due to his own sins, falls in the hell - Raurav
In this world
whatever living beings he has troubled in whatever way,
Then in the other world (afterlife)
When time for providing Yam-Yatna (cruel pain given by death God and His messengers) (because pain purifies from guilt and sin and intense and extreme pains purifies from intense and extreme sins)
At that time, those living beings becomes RURU
And provides pain in the same way to that person.
Because of this RURU creatures, this hell is called RAURAV.
RURU is the name of a creature whose nature is even more cruel then the serpents( of lower Underworld where demons and giant multiheaded cruel serpents resides)