מילון על במדבר 20:36

And the life of Sarah It is not the [usual] way to record the deaths of women, even righteous ones, unless it is by means of a deed. For behold we find only Sarah, Rachel, and Devorah -- Rivka's wetnurse -- and Miriam on the withdrawal of the well. Sarah's death is mentioned since she makes known to us how the grave was acquired with riches (and this is one of the tests [of Avraham]). Devorah's death is mentioned to make known how the name of the place is called Alon-Bachut. Rachel's death is mentioned to teach why she is not buried in Ma'arat haMachpela. And why is it that their years are not numbered, except for Sarah? Since she is the most important of them all.