The Kabalistic correspondence of the Parshiyos of Shema and Vehaya Im Shamoa:[1]
The two Parshiyos of Veahavta and Vehaya found in the Shema correspond to two opposite Divine characteristics found in the Sefiros. Veahavta is a paragraph discussing the love of Hashem and its Divine root is in Chesed. On the other hand, the paragraph of Vehaya discusses the punishments that are received for lack of loving G-d and following the Torah, and its Divine root is in Gevurah. Despite this, we find the following paradox regarding the Divine names to which each paragraph corresponds to. The paragraph of Veahavta contains 42 words and corresponds to the 42 letter Divine name of מ”ב, which is a name found in Gevurah. The paragraph of Vehaya contains 72 words, and corresponds to the 72 letter Divine name of ע”ב, which is a name found in Chesed. Why does the Parsha of Chesed contain a name of Gevurah and the Parsha of Gevurah contain a name of Chesed? The explanation is as follows: Each Sefirah contains both a vessel and Divine light of G-d [i.e. Elokus], known as the Or and Keli. Prior to the world of Atzilus, both the vessel and Or of a particular Sefirah were of the same characteristics and could not be changed. Hence, the Sefirah of Chesed contained both an Or and vessel of Chesed; an Or of Gevurah could not be invested in the vessel of Chesed. However, in the world of Atzilus, a new order was established; the ability of Hiskalelus and Ischalfu Duchtaihu. These concepts mean that the vessels of a Sefirah can now also hold the Or of a different Sefirah, hence creating the concept of Chesed in Gevurah and Gevurah in Chesed. [An analogy can be taken from computer programing; in previous years one could not run a windows program [Or] on an apple computer [vessel], while in recent years the two have become compatible.] Now we can understand why the paragraphs of Shema contain a different characteristic than their Divine name.
Shema paragraph: The paragraph of Shema represents the Or of Gevurah, the Divine name of ,מ”בas it resides in a vessel of Chesed. This is because its purpose involves a passionate love of G-d [i.e. Ratzo], which is a matter of Chesed, but aspires to achieve Mesirus Nefesh, which is an expiry of the soul to above, Bechol Nafshecha, which is an act of Gevurah.
Vehaya paragraph The paragraph of Vehaya represents the Or of Chesed, the Divine name of ,ע”ב as it resides in a vessel of Gevurah. This is because it involves drawing the Divine light of the Sefiros into their vessels [i.e. Shuv], which is a matter of Chesed, although it contains matters of retribution for lack of doing so, which is Gevurah.
[1] Likkutei Torah p. 12b-13a; Addition clarifications taken from Toras Shmuel 1869 p. 245