There are many reasons why the Shabbat before Pesach is called Shabbat Hagadol — the great (big) Shabbat. Rabbi ShneurZalman of Liadi, the founder of Chabad Chassidut, known as the Alter Rebbe, in his Shulchan Aruch (430:1) writes the following reason: “Because on it a neis gadolgreat miracle — took place.” On the tenth of Nissan, which was Shabbat (Gemara, Shabbat 87b), the Jews were instructed to prepare a lamb to be used as a Pesach-offering. When the Egyptian firstborn visited Jewish homes and asked what they were planning to do with the lamb, the Jews replied that they were preparing a Pesach-offering to G‑d, who would kill the Egyptian firstborn. Upon hearing this they went to their parents and to Pharaoh begging them to send out the Jewish people. When they refused, the firstborn declared war against their parents and killed many of them, as it is written in Psalms (136:10), “Lemakeh Mitzrayim bivchoreihem” —“Who struck Egypt through its firstborn.”

What is so unique about this miracle that it should be described as a “neis gadol”“great miracle”?

The Rebbe (see Likkutei Sichot, vol. 14) explains as follows:

Throughout history the Jewish people have been confronted with numerous enemies. Fortunately, Hashem comes to our salvation and miraculously our enemies are destroyed. The uniqueness of the miracle of Shabbat Hagadol was that while Egypt and Pharoah were still in their fullest strength and glory, their own firstborn demanded compliance with G‑d’s will, and when they refused, an internal war erupted, fought on behalf of the Jewish people. Thus, the Egyptians killing Egyptians on behalf of the Jewish people was equivalent to “ithapcha chashocha lenehora” — “transforming darkness to light” — and the greatest miracle that the Jewish people have witnessed.

Based on the Alter Rebbe’s connecting it with the preparing of the lambs for a Korban Pesach, I would like to add another explanation as to why it is called Shabbat Hagadol — the big Shabbat.

The Egyptians visited the homes of their Jewish slaves and were horrified to see how the lambs they worshipped were being prepared. When the Egyptians asked what they were doing with the lambs, the Jews did not try to evade the question. Rather, they proudly proclaimed “We have a G‑d Who commanded us to sacrifice these.”

A major difference between a katan — minor — and a gadol — adult — is that a minor is frequently timid and likely to obscure the truth with excuses. On the other hand, an adult — a big and mature person — is not ashamed, and forthrightly proclaims his convictions.

On this Shabbat the Jews acted as gedolim — big, grownup mature adults — and unhesitatingly proclaimed their allegiance to Hashem. Since they acted like gedolim, this Shabbat is known as Shabbat Hagadol — the big Shabbat.

My dear Bar Mitzvah, by coincidence on this Shabbat you and the Shabbat receive the title gadol — big. Torah now considers you no longer a small little boy, but rather a big — mature — adult. Hopefully just as the Shabbat is called “gadol” because the people acted like big and mature adults and proudly demonstrated their affiliation with Hashem and His commandments, likewise you will, throughout your entire life, be a gadol — big, mature adult — when it comes to your Torah observance. Never be ashamed or embarrassed to declare publicly that you are a member of Klal Yisrael and nothing will stop you from being dedicated to the observance and fulfillment of His Torah and mitzvot.