Reasons for Laining the Daled Parshiyos
Laining Brings Out the Special Qualities of the Time
1. We find in the sefarim hakedoshim that laining a parsha brings out the special qualities of the season. Chazal say (גמ' מנחות דף ק''י ע''א ), Whoever involves himself in the Torah of [the korban] olah is considered to have brought an olah. Thus, Chazal instituted the annual laining of four parshiyos from before Rosh Chodesh Adar until Rosh Chodesh Nissan in addition to the weekly parsha. This helps us inspire ourselves properly during these lofty times. We will go through the reasons.
Shekalim
2. When the Beis HaMikdash stood, every person had to donate every year to the korban tamid fund. We derive from the posuk “זאת עולת חדש בחודשו לחדשי השנה ” that Nissan was the month when the tamid and mussaf korbanos had to be purchased with the new funds. Thus, we make an announcement about the shekalim thirty days before Rosh Chodesh Nissan – i.e., on the Shabbos before or of Rosh Chodesh Adar – that everyone must bring his shekalim on Rosh Chodesh Nissan. In fulfillment of the concept of “ונשלמה פרים שפתינו ,” we lain the beginning of Parshas Ki Sisa, which discusses the topic of the shekalim (מ''ב סי' תרפ''ה סק''א וב').
3. ונשלמה פרים שפתינו. If the Beis HaMikdash were around today, everyone would enthusiastically bring his shekalim to have a share in the korbanos and bring nachas ruach to Hashem. Today, our avoda is to lain the parsha and say the yotzros with kavana and sincere inspiration and feeling, with a burning desire to fulfill the mitzva of shekalim. If we can inspire ourselves to achieve this lofty level, Hashem will long to bring us back to how things once were, with the building of the Beis HaMikdash, so that this mitzva can be fulfilled in deed, not just in word and thought.
Zachor
4. We lain Parshas Zachor the Shabbos before Purim to remember the story of Amalek. We do it near Purim because of the story of Haman, who descended from Amalek. In order to put the remembrance of the eradication of Amalek before the performance, as the posuk says “והימים האלה נזכרים ונעשים,” we lain Zachor before Purim (מ''ב שם ).
5. See Issue 125 regarding whether the chiyuv to lain Zachor is d’oraisa (ibid., par. 1); the chiyuv to understand the meaning of the words and an explanation of them (par. 8); and women’s chiyuv in Parshas Zachor (par. 14).
Parah
6. Chazal instituted the laining of Parshas Parah Adumah before Parshas HaChodesh because the parah adumah was burned in the Midbar close to Nissan in order to sprinkle Klal Yisroel with the ashes as soon as the Mishkan was erected on the 1st of Nissan. The reason was so that everyone would be tahor and able to bring the korban Pesach in its proper time.
7. ונשלמה פרים שפתינו . Thus, we lain this parsha to daven to Hashem that we will also have purifying water sprinkled on us in our days (מ''ב שם ). This parsha was lained even when the Beis HaMikdash was around to exhort people to become tahor so they would be able to bring their korban Pesach in tahara (רש''י מגילה דף כ''ט ע''א ד''ה פרה ).
HaChodesh
8. We lain Parshas HaChodesh the Shabbos before Rosh Chodesh Nissan. The idea is to sanctify the month, as the Torah says, “החודש הזה לכם ראש חדשים,” but this is not the real kiddush hachodesh – that happens when the new moon is sighted, which is when they would sanctify the month in beis din back in the day. This laining is only d’rabanan (מ''ב שם ).