We can't comment on whether you can rebate the commission back to yourself, as this is not an income tax related subject. 

But if you get a cash back rebate on the commission to buy a property, then you would not report it until you sell the property. At that time, you'll deduct the rebate from the adjusted cost base of the property, so it will decrease the total cost you spent to buy it. This may increase the capital gains you have on the sale (if the property is not your principal residence).