Just like every other Greek myth, the story of Cephalus and Procris is way, way old. This one in particular is one of the many tales included in what scholars call the Greek Epic Cycle—it's just a fancy way of referring to a bunch of epic poems by dudes who hung out around the time of Homer.
The bad news? These dudes went around singing all their poems instead of writing them down, so we have no idea what the original myth sounded like.
The good news? We do have a bunch of other versions of the story.
The earliest one we've got comes from an ancient Greet poet name Pherecydes of Athens (guess where he lived), but the most famous versions was written by our main man Ovid, hundreds of years after Pherecydes did his thing. Ovid was so into the tale that he wrote about it twice—once in The Art of Love and again in the Metamorphoses. Even Ovid changed things up between versions: the one in the Metamorphoses adds in the character of Eos. That's right—she wasn't always there.
Other big-deal writers like Hyginius and Apollodorus put their own spin on the myth, and during the Renaissance and later years, it became the inspiration for several operas as well as a new epic poem by English poet Thomas Edwards, who had the good sense to write it down instead of just sing about it. Just saying. (Sorry, civilization, we know writing wasn't a thing way back in the day.)