A proverbial phrase or a proverbial expression is type of a conventional saying similar to proverbs and transmitted by oral tradition. The difference is that a proverb is a fixed expression, while a proverbial phrase permits alterations to fit the grammar of the context.
Another similar construction is an idiomatic phrase. Sometimes it is difficult to draw a distinction between idiomatic phrase and proverbial expression. In both of them the meaning does not immediately follow from the phrase. The difference is that an idiomatic phrase involves figurative language in its components, while in a proverbial phrase the figurative meaning is the extension of its literal meaning. Some experts classify proverbs and proverbial phrases as types of idioms.