In chapter 25, why did Jem not want Scout to tell Atticus about Bob Ewell's comment? Was this a wise thing to ask her to do?

Inof
,tellsthe story of how he and Dill saw Helen Robinson receive the news of
her husband's death. Later in the chapter, Jem tells Scout what he overheard when Stephanie
Crawford was speaking with Aunt Alexandra:

"Mr. Ewell
said it made one down and about two more to go. Jem told me not to be afraid, Mr. Ewell was more
hot gas than anything. Jem also told me that if I breathed a word to , if in any way I let
Atticus know I knew, Jem would personally never speak to me again" (page 245; page numbers
may vary according to the edition).

Bob Ewell wanted Tom
Robinson dead, and he most likely wants to go after anyone else who defended Tom, including
Atticus (who is likely one of the "two more to go"). Jem does not want Scout to tell
Atticus that he has told her this news, as Atticus would not want her to worry. However, Jem
feels that Scout is getting older and is capable of hearing this news.

This
is likely not a wise decision in some ways, as even if Scout knows about Bob Ewell's threats,
she has no way to defend herself. On the other hand, Jem is helping her become more mature by
revealing to her the reality that Bob Ewell is an evil man. Jem should have also told Scout not
to trust Bob Ewell and not to put herself in a vulnerable position, but he tells her that it's
likely an empty threat (while Bob Ewell's threat is not at all empty). By playing down the
likelihood that Bob Ewell will carry through with his threat, Jem does not give Scout a serious
enough warning about what Bob Ewell is likely to do.