Luke 9:60
Jesus said unto him, Let the dead bury their dead: but go thou and preach the kingdom of God.
Matthew 8:22
But Jesus said unto him, Follow me; and let the dead bury their dead.
From http://www.gotquestions.org/let-dead-bury-dead.html
This man may have wanted to fulfill the oldest son’s duty to bury the father, to be near the father in order to obtain an inheritance, or to remain near the body of his father for up to one year to rebury the bones, a practice of some Jews at the time. In any event, Jesus’ answer makes clear that this request would have involved putting tradition or the disciple’s own desires ahead of serving Jesus.