פקוד יפקוד
There was a certain code that was passed down from Yosef all the way to the generation that left Egypt, more than a hundred years after his death. The magic words were פקוד יפקוד, that Hashem would remember עם ישראל when it was time for them to leave Egypt. This was also the sign that the redeemer, would reveal himself that he was sent by G-d, when he would say פקוד יפקוד. The elders recognized that this was the verification that he was sent by Hashem. Moshe Rabbeinu used these words when he first made his appearance with Aharon, that he was Hashem’s messenger. Moshe also needed to use these words when he needed to finds Yosef’s body that was hidden in the Nile. He said, פקוד יפקוד, and Yosef’s casket rose to the top of the Nile. Perhaps when Mashiach comes, he will also come with the words, פקוד יפקוד.