Mark 4:26-29

And he said, So is the kingdom of God, as if a man should cast seed upon the earth; and should sleep and rise night and day, and the seed should spring up and grow, he knoweth not how. The earth beareth fruit of herself; first the blade, then the ear, then the full grain in the ear. But when the fruit is ripe, straightway he putteth forth the sickle, because the harvest is come.