Adldap\Laravel\Auth\DatabaseUserProvider::validateCredentials PHP Method

    public function validateCredentials(Authenticatable $user, array $credentials)
    {
        // Check if we have an authenticated AD user.
        if ($this->user instanceof User) {
            // We'll save the authenticated model in case of changes.
            $user->save();
            return true;
        }
        if ($this->getLoginFallback() && $user->exists) {
            // If the user exists in our local database already and fallback is
            // enabled, we'll perform standard eloquent authentication.
            return parent::validateCredentials($user, $credentials);
        }
        return false;
    }