Yes, you have to, especially if you do not have any new debit transaction after your statement.

Maybank not allow overpayment to your credit card account. Let's say if you try to overpay (without deducting your cashback) using ur m2u savings account, the whole amount will be bounced back to you immediately.

If do balance transfer from other bank also can successfully go through. I used to overpay it this way.