Do sit down

Do sit down.

Don't stand on ceremony.; Please sit down. (A polite phrase encouraging people to resume their seats after rising for an introduction or out of deference.) Tom rose when Mary approached the table, but she said graciously, "Do sit down. I just wanted to thank you again for the lovely gift." Tom:Hello, Bill. Bill (rising): Hi, Tom. Tom (standing): Do sit down. I just wanted to say hello.
See also: down, sit