jQuery validate: custom error message for required field only on specific fields

Question

I follow the suggestion here on how to customize the validation errors of the jQuery validate and it works well.

But right now, I am trying to change the validation message only to specific fields.

I tried assigning a class to the field and did something like but it doesn't seem to be working:

            customRules: function() {

                if (typeof $.fn.validate !== 'undefined') { 
                
                    $.validator.addMethod("check_for_empty", function(value, element, param) {
                        var $ele = $(element);

                        return ! this.optional(element) && value == '';
                    
                    }, $.validator.format("Custom required validation message."));
                }

                if ( $('.custom-required-validation-message input').length ) {
                    $('.custom-required-validation-message input').rules( 'add', {
                    check_for_empty: true
                    });             
                }
            }

Any input would be appreciated. Thanks!