In Judaism, the “evil eye,” ayin hara in Hebrew, is the harmful negative energy that is created when one looks at something with envy or ill feeling.
The idea of an ayin hara is found in many places in the Talmud and Jewish law. For example, we are told not to gaze at a fellow's field of standing grain, lest we damage it with an evil eye.
The concept of an ayin hara is related to the prohibition “Do not covet” in the Ten Commandments.
Wearing an (evil) eye as an amulet is widely believed to provide protection against these evil forces.