needless to say - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Very likely or obvious, self-evident, as in Needless to say, the availability of assault weapons is closely connected with crime. Although nonsensical at first glance (if unnecessary to say, why say it?), this phrase is generally used for emphasis. It originated as needless to speak in the early 1500s. Also see go without (saying).