פירוש על קידושין 6:12

The resolution of how we know that the father receives the money goes back to the original source—the fact that when the daughter sold into slavery goes free, the master does not receive a payment. Had there been a payment, the master would have received it. Thus, logically, in the case of betrothal, where there is a payment, the money goes to the father, who is akin to the master.