What makes you sure it was a parable?
He told his friends (John 11:11): Our friend Lazarus has fallen asleep; but I am going there to wake him up.
His disciples replied, "Lord, if he sleeps, he will get better." JESUS HAD BEEN SPEAKING OF HIS DEATH, BUT HE DISCIPLES THOUGHT HE MEANT NATURAL SLEEP.
So then he told them plainly, "Lazarus is dead, and for your sake I am glad I was not there."
It is certain from the above that the word SLEEP is used as a euphemism at that time. It is used as such by Jesus and others.
We are told that it means DEATH. It does not mean ACTUAL sleep.