php bin/console assetic:dump --env prod causes error

[akilshadi]

I got the following error when i try to execute folowing command in symfony 3 app:
the command:
php bin/console assetic:dump --env prod

the error:

`An error occurred while running:
'/usr/bin/ruby' '/usr/bin/sass' '--load-path' '/Users/shadi.akil/Development/e-box-one/app/../vendor/twbs/bootstrap-sass/assets/stylesheets' '--scss' '--load-path' '/Users/shadi.akil/Development/e-box-one/app/../web' '-
-cache-location' '/Users/shadi.akil/Development/e-box-one/var/cache/prod' '/private/var/folders/xw/3v334ffx03z3zcyw5kgm2nk40000gn/T/assetic_sass36EX92'

Error Output:
/usr/bin/ruby: No such file or directory -- /usr/bin/sass (LoadError)

Input:
/*!

• Bootstrap v3.4.1 (https://getbootstrap.com/)
• Copyright 2011-2019 Twitter, Inc.
• Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  */

// Core variables and mixins
@import "bootstrap/variables";
@import "bootstrap/mixins";

// Reset and dependencies
@import "bootstrap/normalize";
@import "bootstrap/print";
@import "bootstrap/glyphicons";

// Core CSS `