Pubnub One to One Chat Sending Message to all users

This is My Pubnub Chat Code

 var pubnub = PUBNUB.init({
    publish_key   : 'my_key',
    subscribe_key : 'sub-key'
});

  pubnub.subscribe({

    channel : "",

    message : function(m){

     $(".conversation-list").append(
        '<li class="clearfix '+ m.clearifix +' ">' +
        '<div class="chat-avatar">' +
        '<img src="' + m.image + '">'+
        '<i>   </i>' +
        '</div>' +
        '<div class="conversation-text">' +
        '<div class="ctext-wrap">' +
        '<i> '+ m.name + '</i>' +
        '<p>' + m.message + '</p>' +
        '</div>' +
        '</div>' +
        '</li>'
        ).animate({scrollTop: $(".conversation-list")[0].scrollHeight}, 0);
     $('.reply-text').val('');

 },
     //connect : publish
 });

  $('.send-reply-to-user').on('click', function (e) {
    e.preventDefault();

    if ($('.reply-text').val()== '')
        return false;
    else

        console.log(pubnub.publish);
   // console.log(this);

    var user_to_id = $(".send-reply-to-user").attr('user_to_id');
    var message = $('.reply-text').val();
    var name = $('#user_name').val();
    var image = document.getElementById("user_image").getAttribute("src");
    var clearifix = $('#user_clearifx').val();

    pubnub.publish({
        channel : "",
        message: { name : name, message : message, image : image, clearifix : clearifix }
    });

    if ($.trim(message).length != 0) {
        $.ajax({
            url: '',
            cache: false,
            method: 'POST',
            data: {user_to_id: user_to_id, message: message, _token: ''},
            beforeSend: function () {
            },
            success: function (result) {
            }

        })
    }

});

This code is Working perfectly only problem is that messages are going to all users, I want to send msg to one to one user.

Example: User one: John send a message to User two Deo, 
Example 2: John sends a message to Marry

and so on. Using Pubnub JS API, Backend as Laravel 5.6

via Chebli Mohamed