GEN939 The Talmud Baba Metzia 87a states that the Torah teaches us Derech Eretz [proper conduct] from [this verse.] – even a male guest should inquire after the welfare of his host’s wife.   One should not address the host’s wife directly, but instead should address his question to the host.  Some of the Rishonim [11th-15th century Talmud commentators, prior to Shulchan Aruch], however, contest this law, claiming that it is prohibited to inquire about the welfare of the host’s wife.   According to these opinions, [this verse] teaches us that a guest should ask only about the whereabouts of his host’s wife.   However, the halachah follows the opinions that require a guest to inquire about the welfare of the host’s wife Even Haezer 21:6. (Note that the commentators make a distinction between asking about her wife’s welfare and sending regards to the wife, which is prohibited).   WAGS 168-9