dabbrev-search-these-buffers-only

dabbrev-search-these-buffers-only is a variable defined in `dabbrev.el'.
Its value is

nil

Documentation:
If non-nil, a list of buffers which dabbrev should search.
If this variable is non-nil, dabbrev will only look in these buffers.
It will not even look in the current buffer if it is not a member of
this list.

You can customize this variable.