display validation in modal using ajax in php codeigniter

Question

$(document).on('click', '#add', function(e) { e.preventDefault();

            var user_name = $("#user_name").val();
            var email = $("#email").val();
            var password = $("#password").val();
            var number = $("#number").val();

            $.ajax({
                url: "<?= site_url('Users/insert'); ?>",
                type: "POST",
                dataType: "json",
                data: {
                    user_name: user_name,
                    email: email,
                    password: password,
                    number: number
                },
                success: function(data) {

                    if (data.response == "success") {
                        $('#add_modal').modal('hide')
                        $("#form")[0].reset();
                    }
                }
            });
        });

validation error
form_validation error display error