For himself Adam ordained forty days of fasting, while he stood in the river Jordan in the same way as Eve was to take up her stand in the waters of the Tigris. After he had adjusted the stone in the middle of the Jordan, and mounted it, with the waters surging up to his neck, he said: "I adjure thee, O thou water of the Jordan! Afflict thyself with me, and gather unto me all swimming creatures that live in thee. Let them surround me and sorrow with me, and let them not beat their own breasts with grief, but let them beat me. Not they have sinned, only I alone!" Very soon they all came, the dwellers in the Jordan, and they encompassed him, and from that moment the water of the Jordan stood still and ceased from flowing.
Adam Fasted Forty Days in the Jordan River
Legends of the Jews 2:86