Why the Children of Joseph Are Shielded From the Evil Eye

"And the children of Joseph spoke to Joshua, saying: Why have you given me one lot and one portion as an inheritance, seeing I am a great people, since hitherto the LORD has blessed me" (Joshua 17:14) — and gave me twenty thousand five hundred more than my brother Ephraim in the order of Pinchas, and the blessing "so shall your seed be" was fulfilled in me. "And Joshua said to them: If you are a great people, get up to the forest" (Joshua 17:15) — go and hide yourselves in the forests, so that the evil eye not have power over you. They said to him: We come from the seed of Joseph, over whom the evil eye has no power, as it is written of him, "Joseph is a fruitful vine, a fruitful vine by a fountain [alei ayin]" (Genesis 49:22). And Rabbi Abbahu said: Do not read "by a fountain [alei ayin]" but "rising above the eye [olei ayin]" [i.e., above the power of the evil eye]. Rabbi Yose bar Hanina said: From here — "and let them grow into a multitude [ve-yidgu] in the midst of the earth" (Genesis 48:16): just as fish [dagim] of the sea, over whom the evil eye has no power, so too the seed of Joseph, over whom the evil eye has no power.