What message does Dick send to Oliver?

Dick is dying whe he says he'd like to leave Oliver his love, and to tell him that he (Dick) is happy that he will die young, because it means his sister will not have forgotten him.

‘I should like,’ said the child, ‘to leave my dear love to poor Oliver Twist; and to let him know how often I have sat by myself and cried to think of his wandering about in the dark nights with nobody to help him. And I should like to tell him,’ said the child pressing his small hands together, and speaking with great fervour, ‘that I was glad to die when I was very young; for, perhaps, if I had lived to be a man, and had grown old, my little sister who is in Heaven, might forget me, or be unlike me; and it would be so much happier if we were both children there together.’