Esther 2:21-22

21During the time Mordecai was sitting at the king’s gate, Bigthana Hebrew Bigthan, a variant of Bigthana and Teresh, two of the king’s officers who guarded the doorway, became angry and conspired to assassinate King Xerxes. 22But Mordecai found out about the plot and told Queen Esther, who in turn reported it to the king, giving credit to Mordecai.