gnus-treat-hide-citation

gnus-treat-hide-citation is a variable defined in `gnus-art.el'.
Its value is

nil

Documentation:
Hide cited text.
Valid values are nil, t, `head', `first', `last', an integer or a
predicate. See Info node `(gnus)Customizing Articles'.

See `gnus-article-highlight-citation' for variables used to
control what it hides.

You can customize this variable.