פירוש על קידושין 46:3

Elsewhere R. Huna son of R. Joshua says that priests serving in the Temple are agents of God and not agents of the people whose sacrifices they are offering. They cannot be our agents because an agent should not be able to do something that the person sending him cannot do himself. But now we do have a case of an agent being able to do something that the person himself cannot do. A slave’s agent can accept the slave’s deed of manumission, whereas the slave himself cannot.
Thus we have a difficulty on R. Huna.