Matthew Henry Commentary Esther 2:21-23

"In those days, while Mordecai was sitting in the king`s gate, two of the king`s chamberlains, Bigthan and Teresh, of those that kept the threshold, were wroth, and sought to lay hands on the king Ahasuerus. And the thing became known to Mordecai, who showed it unto Esther the queen; and Esther told the king [thereof] in Mordecai`s name. And when inquisition was made of the matter, and it was found to be so, they were both hanged on a tree: and it was written in the book of the chronicles before the king." — Esther 2:21-23 (ASV)

Good subjects must not conceal any evil plot they know of against the prince or the public peace. Mordecai was not rewarded at the time, but a remembrance was written.

Thus, with respect to those who serve Christ, though their reward is not until the resurrection of the just, yet an account is kept of their work of faith and labour of love, which God is not unrighteous to forget. The servant of God must be faithful to every trust and watchful on behalf of those who employ him. If he appears to be neglected now, he will be remembered hereafter.

None of our actions can be forgotten; even our most secret thoughts are written in lasting records (Revelation 20:12).