Why do Jews use the symbol of a hexagram or Magen David?
and "baraqemet", who is a regular member in this Forum, mentioned in his answer the seal from the seventh century B.C.E. found in Sidon and belonging to one Joshua ben Asayahu which is mentioned in Gershom Sholem’s classical article about the Star of David. baraqemet commented:
All we have is a statement by someone [Gershom Sholem], who is into kabbalah, who did not supply any proof to support their theories.
I don't want the bother of registering to the above-mentioned Forum but I happen to know the missing source:
David Diringer, Le Iscrizioni Antico-ebraiche Palestinesi, Pub; Icazioni Dell'Universita Di Firenze, Facolta' Di Lettere E Filosofia; 3, Firenze: Le Monnier, 1934, P. 187
Check it out!