Saying a baby is beautiful may bring bad luck, so superstitious people often pretend to be spitting and say to the child, "Let me not give you the evil eye."
I have checked the meaning of the word spit: 1- force out the contents of mouth esp saliva 2- say words quickly and angrily. Which one is correct here number one or two.
Spitting (meaning 1) is one of the traditional superstitions of folklore, from many cultures, that is believed to protect against the "evil eye'.
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Popular Superstitions - My Jewish Learning