chukas

Right after the Torah tells us the laws of the פרה אדומה, it says ותמת שם מרים; Miriam died there.
Rashi asks, why did the Torah put these next to each other? He answers that it's to teach us that just like קרבנות are מכפר, the death of צדיקים is also מכפר.
Right after the death of Miriam comes the episode of Moshe hitting the rock instead of talking to it. רבינו בחיי says, the reason it's right after is because that was the cause of Moshe & Aaron dying in the midbar, & not being able to enter the land of Israel.
The gemara in chulin tells us the story of R' Pinchas ben Yair whose donkey wouldn't eat from grain that didn't have maaser taken off. It says, if even the animals of צדיקים are protected from causing their owner to sin,all the more so no bad will come because of the tzadik himself.
Based on that, how could it be that miriam could be the cause of her brothers' death & them not being able to enter the land?
The navi in yeshaya says, הצדיק אבד ואין איש שם על לב the righteous one perishes and no man takes it to heart. ואנשי חסד נאספים באין מבין כי מפני הרע נאסף הצדיק; men of kindness are gathered in with no one understanding that because of the impending evil the righteous one was gathered in. There are two explanations given for the words "that because of the impending evil the righteous one was gathered in." One is that we learn from our Posuk that the death of צדיקים is מכפר, and two, that the צדיק goes before the bad comes so he doesn't have to see it. As the gemara says, when a צדיק leaves the world, bad comes.
We need to understand how the two reasons can coexist since once the death of the צדיקים was מכפר, why should bad befall us? Says the נודע ביהודה that צדיקים die because of the sins of the generation, but if after the death of the צדיק the people take it to heart & repent, 'ה will forgive them & no more evil will befall them. In this case the death will be a kapara. However, if we don't take it to heart, then the punishment will come & 'ה will take more צדיקים so that they don't see the evil that can befall us for not taking it to heart and repenting.
Right after the death of miriam what did the jews do? They went to moshe complaining, we have no water, why did you bring us here to die? We should have stayed in Egypt.
They didn't learn anything from the death of miriam; just the opposite. They started complaining again, so her death couldn't be a kapara for them. And it was the sinfulness of the nation that caused Moshe & Aaron to die & not be able to go into the land, not Miriam.
We have to learn from here not to take the death of צדיקים lightly, and to learn from their ways how to better ourselves. 'ה shouldn't have to take any more tzadikim away from us, but instead grant them long life so we can emulate them & get the kapara that we so desperately need!