E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
When the Spartans seized upon Thebes, they placed Archias over the garrison. Pelopidas, with eleven others, banded together to put Archias to the sword. A letter containing full details of the plot was given to the Spartan polemarch at the banquet table; but Archias thrust the letter under his cushion, saying, Business tomorrow. But long ere that sun arose he was numbered with the dead.