Kautilya's Arthashastra 7.17.35

7.17.35

te kumāraṃ paraṃparayopatiṣṭheran //

Whoever is rising in power may break the agreement of peace. Carpenters, artisans, and other spies, attending upon the prince (kept as an hostage) and doing work under the enemy, may take away the prince at night through an underground tunnel dug for the purpose. Dancers, actors, singers, players on musical instruments, buffoons, court-bards, swimmers, and saubhikas (?), previously set about the enemy, may continue under his service and may indirectly serve the prince. They should have the privilege of entering into, staying in and going out of, the palace at any time without rule. The prince may therefore get out at night disguised as any one of the above spies.