Several different explanations have been given for why the Shabbat preceding Pesach is given the name "Shabbat Ha'gadol" – literally, "the Great Shabbat." One of the lesser-known reasons is a fascinating connection between this Shabbat and Abraham Abinu. The Gemara in Masechet Rosh Hashanah (11) brings a debate between Rabbi Eliezer and Rabbi Yehoshua as to the month in which the Abot (patriarchs) passed away. Rabbi Yehoshua maintained that the three Abot – Abraham, Yishak and Yaakob – died during the month of Nissan, whereas Rabbi Eliezer was of the opinion that they passed away during Tishri. However, a different source – the Yalkut Reubeni (in Parashat Lech-Lecha) – states that Abraham Abinu died during the month of Tebet. This is alluded to in G-d's promise to Abraham, "Tikaber Be'seba Toba" – that he would be buried at an advanced age (Bereshit 15:15). The first letters of these three words (Tav, Bet, Tet) are the three letters of the word "Tebet," and the word "Toba" resembles "Tebet." This is mentioned also in the work Seder Ha'dorot (Rav Yehiel Heilprin, 1660-1746). The obvious question arises as to how to reconcile this theory with the Gemara, which indicates that Abraham died either in Nissan or in Tishri. The Hida (Rav Haim Yosef David Azulai, 1724-1806) answers this question by citing a Kabbalistic source about the unique nature of the month of Nissan. The Torah designates Nissan as the first month of the year, and according to the teachings of Kabbalah, this month contains within it an element of all other months. Each of the first days of Nissan corresponds to a different month of the year. Rosh Hodesh Nissan is associated with Nissan itself, whereas the 2 nd of Nissan is associated with Iyar, the 3 rd is connected to Sivan, the 4 th to Tammuz, and so on. Accordingly, the sources that say that Abraham died in Tebet could be understood to mean that he died on the day of Nissan – following Rabbi Yehoshua's opinion – corresponding to the month of Tebet. As Tebet is the tenth month, this would mean that Abraham Abinu died on the 10 th of Nissan. As we know, the 10 th of Nissan is a very significant date – as it was on this day when, just before the Exodus from Egypt, Beneh Yisrael prepared the sheep for the Pesach sacrifice which they offered on the afternoon of the 14 th of Nissan (Shemot 12:3) in preparation for their departure from Egypt. Now in the year of the Exodus, the 15 th of Nissan – the day Beneh Yisrael left Egypt – fell on Thursday, such that the 10 th of Nissan fell on Shabbat. It emerges, then, that Shabbat Ha'gadol marks the Yahrtzeit of Abraham Abinu. On this basis, it has been explained why this Shabbat is given the name "Shabbat Ha'gadol." A verse in the Book of Yehoshua (14:15) speaks of a great man – "Ha'adam Ha'gadol Ba'anakim" – who lived in Hebron, and our Sages teach that this refers to Abraham Abinu. As he is the "Ha'adam Ha'gadol," the Shabbat before Pesach, which commemorates his Yahrtzeit, is called "Shabbat Ha'gadol."