Histories

They were found still living and brought into the king's presence; then Xerxes, having inquired of them the purpose of their coming, ordered his guards to lead them around and show them his whole army. When the spies had seen all to their heart's content, they were to send them away unharmed to whatever country they pleased.

The reason alleged for his command was this: had the spies been put to death, the Greeks would not so soon have learned the unspeakable greatness of his power, and the Persians would have done their enemy no great harm by putting three men to death. Xerxes said that if they should return to Greece [22,39] (nation), EuropeHellas, the Greeks would hear of his power and would surrender their peculiar freedom before the expedition with the result that there would be no need to march against them.