Esther 2:22 (ESV)

22 And this came to the knowledge of Mordecai, and he told it to Queen Esther, and Esther told the king in the name of Mordecai.

Mordecai could not have known how much his people, and he himself, would later benefit from his discovery and his act of loyalty toward the king. For the time, he acted from a sense of duty, and possibly in order to protect Esther from harm.

Esther reported the news of the conspiracy to the king, making sure that he understood where the news had come from. Persian kings usually bestowed great rewards, such as large pieces of land and high positions, on those who had proved themselves loyal to the throne.