Esther 2:21-23

2:21 In those days while Mordecai was sitting at the king’s gate, Bigthan and Teresh, two of the king’s eunuchs who protected the entrance, became angry and plotted to assassinate King Ahasuerus. 2:22 When Mordecai learned of the conspiracy, he informed Queen Esther, and Esther told the king in Mordecai’s behalf. 2:23 The king then had the matter investigated and, finding it to be so, had the two conspirators hanged on a gallows. It was then recorded in the daily chronicles in the king’s presence.

Esther 6:2

6:2 it was found written that Mordecai had disclosed that Bigthana and Teresh, two of the king’s eunuchs who guarded the entrance, had plotted to assassinate King Ahasuerus.