The icons, who starred as Han Solo and Luke Skywalker, first met at their "Star Wars" screen test, which circulated on Twitter this week.
In the clip, the duo recites lines from the original script for "Star Wars: A New Hope."
Entertainment Weekly reports that the lines didn't make the movie's final cut.
Mark Hamill replied to a tweet of the snippet, writing, “My screen-test for @starwars w/ Harrison on the 1st day I ever met him. Neither 1 of us had read the script at this point, only this 1 scene.”
"I asked George what kind of movie it was," he recalled. "'Let's just do it, we'll talk about that later.' We never did talk about it later — we just did it."
Ford and Hamill starred in four "Star Wars" movies together, but haven't shared a scene since 1983's "Return of the Jedi."
Ford's most recent "Star Wars" appearance was in 2015’s "The Force Awakens."
Hamill will reportedly appear in December's "The Rise of the Skywalker."