create custom rule and its message in laravel code example

Example 1: laravel validation

/**
 * Store a new blog post.
 *
 * @param  Request  $request
 * @return Response
 */
public function store(Request $request)
{
    $validatedData = $request->validate([
        'title' => 'required|unique:posts|max:255',
        'body' => 'required',
    ]);

    // The blog post is valid...
}

Example 2: custom rule laravel validation

public function store()
{
    $this->validate(request(), [
        'song' => [function ($attribute, $value, $fail) {
            if ($value <= 10) {
                $fail(':attribute needs more cowbell!');
            }
        }]
    ]);
}