From the book Karma and Creativity:
This passage is from the Bradaranyaka Upanisad.
"Now as a caterpillar, when it has come to the end of a
blade of grass, in taking the next step draws itself together
towards it, just so this soul in taking the next step strikes
down this body, dispels its ignorance, and draws itself
In Hindu tradition, perhaps the earliest hint of the notion of rebirth is found here, contemporaneous with the rise of Buddhism.