Comment on the ethics and business proposition of the following referral arrangement?

During our discussions "Prospecting", we discussed means of prospecting and different prospecting methods. Assume that you are now licensed to sell Mortgages and for that you have developed a good referral network with 4 reputable accountants in your community. All these sources refer you business on a regular basis. You feel obliged to these sources and want to show your appreciation by rewarding them with a referral fee that is 20% of the commission you earn from every client referred to you with whom you end up doing business.