The phrase "immortal words" refers to something that is said or written and remembered forever, never losing its importance or impact over time. Full definition
In immortal words of Eurythmics, everybody's looking for something. (skadate.com)
I couldn't help but recall Twain's immortal words when I read a recent article about the launch of NOOK PressTM. (womensmemoirs.com)
It starts in 1963 with the March on Washington when King spoke immortal words to more that 200,000 people from the steps of the Lincoln Monument. (fadmagazine.com)