Midrash sobre Salmos 78:8

Rabbi Eliezer said: During all those years, when the Israelites abode in Egypt, they dwelt securely and peacefully at ease until Ganoon, one of the grandchildren of Ephraim, came and said to them, The Holy One, blessed be He, has revealed Himself to me, to lead you out of Egypt. The children of Ephraim, in the pride of their heart, for they were of the royal seed, and mighty men in battle, took their wives and their sons, || and they went forth from Egypt. The Egyptians pursued after them, and slew of them 200,000, all of them mighty men, as it is said, "The children of Ephraim, being armed and carrying bows, turned back in the day of battle" (Ps. 78:9).