Is there any actual mekor for the common belief that saying bli ayin hara will prevent one from happening? thanks!!!!
The idea here is that if a person says something that might cause an ayin hora, that he should bentch the person, as a measure of counteracting it. This idea is mentioned by the Chida in Tziporen Shamir -172, Shmiras Haguf V’hanefesh 241-1, Mishnas Moshe (Blau) pg. 34 in the name of Divrei Torah 6-7.