ShowValidationSummary

<form id="myform">
    <input name="username" required /> <br />
    <button>Save</button>
    <button id="hide" type="button">Show Summary</button>
</form>

<script>
    // attach a validator to the container and get a reference
    var validator = $("#myform").kendoValidator({
      validationSummary: false
    }).data("kendoValidator");

    // trigger validation
    validator.validate();

    //show the validation summary when show button is clicked
    $("#hide").click(function() {
        validator.showValidationSummary();
    });
</script>