Driven mad by Hera, Hercules slew his own six sons. After recovering his sanity, Hercules deeply regretted his actions; he was purified by King Thespius, then traveled to Delphi to inquire how he could atone for his actions. There the oracle Pythoness advised him to reside at Tyrins and serve King Eurystheus for twelve years, performing whatever labour might beset him; in return, he would be rewarded with immortality. Hercules despaired at this, loathing to serve a man whom he knew to be far inferior to himself, yet afraid to oppose his father Zeus. Eventually he placed himself at Eurystheus's disposal.