Esther 2:21-22

Now Bigthana and Teresh were two of the king’s eunuchs who guarded the doorway. While Mordecai was sitting at the king’s gate, they became angry and began to make plans to kill King Xerxes. But Mordecai found out about their plans and told Queen Esther. Then Esther told the king how Mordecai had discovered the evil plan.