Question
Where does it say that a man should not walk between two women?
Answer
The source is Talmud Pesachim 111a, which lists persons of the opposite sex (i.e., a man shouldn’t pass between two women or vice versa), dogs, palm trees, pigs, and snakes. Talmud Horayos 13b says the same thing about camels. The Talmud indicates that doing these things is bad for the memory; but these passages are omitted from the standard law codes.