The korban Pesach (Pascal sacrifice) was offered only once during the Jews' 40 years of wandering in the desert, one year after the Exodus, at the express command of G-d, as it states in this week's Torah portion, Beha'alotcha: "In the second year of their going out from the land of Egypt, in the first month...and the Children of Israel made the Passover offering in the proper season."
For the next 39 years there was no korban Pesach, as G-d stipulated that it could only be offered after the Jews entered Israel. In fact, the bringing of the Pesach sacrifice resumed only after the Jews had taken possession of the land, where upon it was sacrificed every year.
Rashi, the foremost Torah commentator, interprets the Jews' failure to bring the korban Pesach in the desert in a negative light, despite the fact that G-d had told them to wait. "This was to the disgrace of Israel, that all 40 years they were in the desert they offered only one Pascal sacrifice."
But how can Rashi fault them for following G-d's command? What could possibly be shameful about not offering a sacrifice when they were not required to do so?
The "disgrace," however, was in the Jews' meek acceptance of the prohibition. Had they begged and pleaded with G-d, surely He would have allowed them to offer it, even in the desert.
Rashi thus finds it shameful that 39 years elapsed during which the Jews were silent. Praiseworthy behavior, by contrast, would have been to repeatedly beseech G-d until He acquiesced to their demand.
In truth, had the Jewish people requested permission to offer the korban Pesach before reaching Israel, G-d would have allowed it, just as He gave the Jews who were ritually impure on Pesach a second chance to bring an offering on Pesach Sheini. For G-d listens to our requests. Had the Jewish people but asked, they would have merited to bring the korban Pesach even in the desert.
From this we learn just how important G-d considers a Jew's requests. Asking something of G-d is praiseworthy; not asking Him is "disgraceful."
This also teaches how important it is to repeatedly entreat G-d to bring the Final Redemption "speedily," as we say in our prayers, "Speedily cause the scion of David Your servant to flourish," and "May it be Your will...that the Holy Temple be speedily rebuilt in our days."
The initiative must come from us. We must continually beg G-d to bring Moshiach. For when Jews ask, G-d listens.
Adapted for Maayan Chai from Likutei Sichot, Volume 23