The first stories of Jason were likely told in Mycenaean Greek, an early dialect of what would become Classical Greek. The Greek sources listed below cover the nearly all of Antiquity, from Homer and Hesiod (c. 700 BCE) to the gradual fading away of the Classical world around the time of the Orphic Argonautica (c. 450 CE).
GREEK EXCERPTS AND FRAGMENTS
Containing brief mentions from longer texts and surviving bits of early authors' works
PINDAR'S FOURTH PYTHIAN ODE
The earliest surviving complete Jason poem.
The play that defined the myth of Medea.
References to Jason and the Argonauts in the mystical epic of the Trojan War.
APOLLONIUS OF RHODES' ARGONAUTICA
The Hellenistic epic that serves as the de facto definitive version of the myth.
DIODORUS SICULUS' LIBRARY
The section on the Argonauts from Diodorus' universal library.
The section on the Argonauts from (pseudo) Apollodorus' library of mythology.
The last Greek Jason epic, written from Orpheus' point of view.