Esther 6:2 (ESV)

2 And it was found written how Mordecai had told about Bigthana and Teresh, two of the king’s eunuchs, who guarded the threshold, and who had sought to lay hands on King Ahasuerus.

Earlier in the story, we read of Mordecai’s acts to save Ahasuerus from the murderous plot of two of his officials. This event was recorded in the book of chronicles (or annals, Esther 2:23).

After some time of reading, the servant chanced upon this specific entry.