old saw

A proverb or maxim, as in Mom's always repeating the old saw, “Haste makes waste.” This term uses saw in the sense of “saying,” and old in the sense of “wise” rather than old-fashioned. [Second half of 1400s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.