Parshas Chukas

(The Segulah of Learning Zera Shimshon)

Rashi in Bamidbar tells us that Miriam HaNaviah's death is written about after the section regarding Parah Adumah to tell us that the death of a tzadik(es) atones for sins the same way a Parah Adumah does.

The Zera Shimshon asks if this is so, why doesn't the Torah write about Miriam's death after the section regarding karbanos that atone for sins (like the chatas) rather than the Parah Aduma which effectively "just" makes those impure pure?

He explains that talking about the death of Miriam after Parah Aduma teaches us an added condition. It isn't just the death of the tzadik that atones, just as with the Parah Aduma the person doesn't just become pure solely from the Kohen sprinkling the ashes. With the Parah Aduma, the person has to not only have the Kohen purify him by sprinkling him with the ashes mixed with water, he must also act on his own behalf and go to the mikveh. We learn too that the death of a tzadik does not automatically bring atonement. The people must also internalize the pain from the loss of such a great person, and this pain will bring them to do teshuva. The teshuva, the people acting on their own behalf, will bring the atonement.

Source: Zera Shimshon Parshas Chukas