[If] someone eats terumah by mistake, he pays the principal plus a fifth. Whether one eats, drinks, or anoints, whether it is te-rumah which is tahor or terumah which is tamei, he pays its fifth and a fifth of its fifth. He does not pay [with] terumah, but with tithed chullin, and these [tithed chullin] become terumah, and the payment is terumah. If the Kohen wanted to forgive [this payment], he cannot forgive [it].