Midrash su Giudici 5:18

"and the treasures hidden in the sand": "treasures" — chilazon; "hidden" — tarith (a valuable fish); "sand" — white glass. For the tribe of Zevulun protested before the L-rd, as it is written (Judges 5:18) "Zevulun is a people that risked its life to the death, etc." and he said before Him: "L-rd of the Universe, to my brothers You gave lands, and to me You gave seas and rivers." The L-rd: "They will need you for the chilazon (found in your territory)." Zevulun: "Who shall inform me?" (i.e., What assurance have I that they are taking chilazon and will pay me for it?) The L-rd: Let this be a sign for you: If anyone steals it, his "merchandise" will not prosper (i.e., the precious dye of the chilazon will not take).