Esther 3:10 (ESV)

10 So the king took his signet ring from his hand and gave it to Haman the Agagite, the son of Hammedatha, the enemy of the Jews.

In the case of the former queen Vashti, the king had consulted his advisers first. But this time, when it came to the massacre of an entire people-group (of which Haman did not even give the name!), he gave his approval instantly.

Without any questions, he took off his signet ring (which, in ancient times, functioned as a signature) and entrusted it to Haman. Haman could now issue any decree he wished. Suddenly, the Jews were under the power of a man whom the author ominously describes as Haman the Agagite, the son of Hammedatha, the enemy of the Jews.