Why do we read the complete hallel for only the first day of Pesach but not the rest of the holiday? I think this is different than on Chanukah when we read the complete hallel for the entire holiday. Weren’t the miracles that occurred regarding Pesach greater than Chanukah?
After departing Egypt on what became the first day of Passover, the Jews reached the Sea of Reeds (Red Sea) on the seventh day. As you know, they were pursued by the Egyptians in chariots of war led by Pharaoh who intended to annihilate them. Trapped with the sea before them and the Egyptian army rapidly approaching from behind, the Jews turned their hearts upward. In that merit, G-d miraculously split the sea and the Jews passed through.
As the last Jews exited the sea, the last of the Egyptians had finished entering in after them. The raging waters held at bay were let loose with a fury and drowned the entire Egyptian army. Having witnessed this awesome miracle and surreal salvation, the Jews broke out in song and praise of G-d, “Then Moses and the children of Israel sang this song to the L-rd, and they spoke, saying, I will sing to the L-rd, for very exalted is He; a horse and its rider He cast into the sea” (Ex. 15:1).
According to the Midrash the angels observed all this from on high and also wanted to chime in and praise. G-d reprimanded them saying, “My creations are drowning in the sea and you wish to sing?!” From here we learn that that the joy of the salvation must be tempered by sorrow over the destruction of the enemy, as in the verse “Do not rejoice in the downfall of your enemy” (Prov. 24:17).
Therefore, the hallel of this day, the seventh day of Pesach, is not completed since our joy over the miraculous salvation at the sea is marred by the loss of life of the Egyptians. And since the hallel is not completed on this last day, it’s abridged for the intermediate days as well, so that they should not be viewed as more important than the concluding festival day.
You might ask, If G-d stopped the angels from singing, why did Moses and the Jews sing — and why didn’t G-d stop them as he stopped the angels? And if He didn’t stop them, then why shouldn’t we sing as well? Furthermore, according to this, we shouldn’t complete the hallel on the first day either, as there was also great loss of life in the plague of the firstborns. Why do we complete it then? Well, I’m glad you asked. All can be answered with the same idea.
G-d did not allow the angels to sing because they were only spectators and did not actually experience the miracle themselves. They were therefore expected to consider both the salvation and the destruction simultaneously and reduce their joy. However, the Jews of that generation had actually lived through the most harrowing of experiences and literally saw G-d’s salvation with their own eyes. Their joy was completely focused on the miracles, then, and not on the destruction. Accordingly, this reason also applies to future generations of Jews who did not actually experience the miraculous salvation but were more like distant spectators. Therefore we don’t complete the hallel on this last day, or on the intermediate days either, as explained above.
However, the reason we do complete the hallel on the first day despite the destruction of G-d’s creatures in the plague of the firstborns is based on the injunction incumbent on every Jew to view himself as if he had actually partaken in the exodus from Egypt. Since our appreciation and joy is to be so great that we are to feel as if we had actually experienced the exodus ourselves, for this reason we recite the complete hallel on the first night and day of Pesach.