Kabbalah zu Bamidbar 24:3

Of Bilaam, it is written: "The speech of the man whose eyes are open" (Num. 24:3), meaning that he had an evil eye, and wherever he looked, he drew the spirit of destruction on it. That is why he wanted to gaze on Yisrael, so that he could destroy all that his eye could see. Thus, it is written: "And Bilaam lifted up his eyes" (Ibid. 2), meaning he raised one eye and lowered the other, attempting to gaze on Yisrael with the evil eye.