validate() function is not working in PostsController

After submit the data from create view(PostsController) request goes to store method(PostsController)but neither data is validating nor throwing an error.

after removing the validate(), it is working and output is: 123

class PostsController extends Controller
{
.
..
...
public function store(Request $request)
    {
       $this->validate($request, [
            'title' => 'required',
            'body' => 'required',
             ]);
       return 123;
    }

}


Output after the validate the data:

123

via Chebli Mohamed