Can't install SASS on MAC OS, why Operation not permitted?

Question

Command line

Installed Ruby.
I install SASS:
sudo gem install sass
And I see this:

Fetching: sass-3.4.21.gem (100%)
ERROR:  While executing gem ... (Errno::EPERM)
    Operation not permitted - /usr/bin/sass

I try without sudo
gem install sass
and see this:

Fetching: sass-3.4.21.gem (100%)
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.

When installing compass, everything is the same

Answer 1

Try running with the following line:
sudo gem install -n /usr/local/bin sass