"And he sent forth a raven" (Gen. viii. 7). The raven remonstrated,
remarking, "From all the cattle, beasts, and fowls thou sendest none but
me." "What need has the world for thee?" retorted Noah; "thou art good
neither for food nor for sacrifice." Rabbi Eliezer says God ordered Noah
to receive the raven, as the world would one day be in need of him.
"When?" asked Noah. "When the waters are dried up from off the earth,
there will in a time to come arise a certain righteous man who shall dry
up the world, and then I shall want it." This explains what is written
(1 Kings xvii. 6), "And the ravens brought him bread and flesh in the
morning."

THE MIDRASHIM, _Bereshith Rabbah_, chap. 33.