Shabbath Parah (about the Parah Adummah (red heiffer) always falls on the Shabbath preceding Shabbath HaHodesh (the Shabbath before the month of Nissan). This is because the Parah Adummah was burnt in the wilderness close to the month of Nissan, in order to purify Benei Yisrael so that they could offer the Pesah (Passover sacrifice) at the correct time.
Every year, through the reading of the portion of the Parah Adummah with the congregation, the roots of this precept are re-awakened in Heaven. Therefore, if we read this portion every year and connect it to Teshubah (repentance) we purify our souls. It is considered, in fact, as if we performed the actual act of the Parah Adummah, as it says: "Unshallemah Farim Sefathenu" (the words of our lips shall be instead of oxen).
Every person, therefore, while Parashath Parah is being read in the Synagoue, should pay close attention, and request from G-d that He will accept his repentance and then purify him. The repentance has to come first, because it is like a robber. There is no point locking the door while he is still inside. First we must remove him, and then we lock the door.
(See Dabar Be'Itto, Derush Parashath Parah)
