Contributed by: Nissim Alouf
In the Torah we find that the holiday of Pesah is called Hag Hamassot, yet when we speak of this holiday we all use the name Pesah. Why not always use the name from the Torah of Hag Hamassot?
We can answer this question with a Gemara in Masechet Berachot (6a). The Gemara teaches us that Hashem was seen by Moshe as a hazan, wrapped with a talet and tefillin. The Gemara ponders what was written on the scrolls inside Hashem's tefillin. The Gemara answers:
.ומי כעמך ישראל גוי אחד בארץ
"Who is like Your nation, [Hashem,] a unique nation on earth."
Conversely, the Gemara asks what is in the tefillin of Bnei Yisrael, and answer Shemah and Qadesh Li. The theme in all the various parshiyot in our tefillin is the recognition that Hashem is our God, and remembering all the miracles and promises that He made to His people. The tefillin of Hashem glorify Bnei Yisrael, while the tefillin of Bnei Yisrael glorify Hashem.
Bnei Yisroel call the holiday Pesah to remember the great miracle that Hashem performed for us when He was passed over (pesah=Hebrew for Passover) the Jewish homes, and entered only Egyptians homes, killing all their first-borns, resulting in our immediate redemption from Egypt. We therefore call the holiday Pesah to remember our connection to the Boreh, glorifying what He did for us.
On the other hand, in the Torah refers to Pesah as Hag Hamassot, Bnei Yisrael is being glorified!
When Bnei Yisroel were told to leave Egypt, the nation hurried and rushed to the point where eighteen minutes (the time that it takes to make flour into hames) was too long! This name of the holiday connotes the level of sacrifice in Bnei Yisrael's enjoyment of finally being set free, to run and join company with Hashem. Their devotion was unparalleled. Therefore, the Torah calls the holiday Hag Hamassot, as it is Hashem's way to adorn Himself with our uniqueness as His glory.