What is the evil eye in Judaism?

In the sources

The Talmud takes the evil eye seriously: Rav said that most deaths in his day came from it. The sages also taught that Joseph’s descendants are protected from it, because Joseph did not look at what was not his (Genesis 49:22). The Mishnah lists “an evil eye” among the things that “remove a person from the world” (Pirkei Avot 2:11) – meaning a mean-spirited, envious outlook.

A moral idea

Many commentators explain the concept ethically. Showing off wealth, children or success provokes envy and division; looking at others with resentment poisons the one who looks. The cure is a “good eye” – generosity and happiness for another’s success – which Pirkei Avot praises as the best trait.

Customs

Some communities avoid counting people directly or calling up two brothers one after another, and many add “bli ayin hara” (“without the evil eye”) when praising. Hamsa amulets and red strings are popular folk practices; rabbinic authorities differ about them, and they are not part of Jewish law. Faith in God and good deeds are the traditional protection.

The Shulchan Aruch

The halachah itself mentions the evil eye: a person should not stand in his neighbour’s field when its grain is standing, so as not to harm it with his eye (Bava Metzia 107a). About such folk dangers the Talmud also says that “one who is not particular about them, they are not particular with him” (Pesachim 110b) – which is why many rabbis advise modesty without anxiety.