Wiktionary
old saw
n. (context idiomatic English) a cliché, saying, or overused expression; especially a proverb or maxim
Usage examples of "old saw".
So why did she feel, as they said in the old saw Keff had once dug up in his linguistical research, as if a goose had walked over her grave?
What this seems to reflect is some version of the old saw that in SF.
Although he was no longer officially under arrest, and thus under no obligation to remain in the cabin, he decided that the old saw about discretion being the better part of valor applied in this case.