Leviticus 27:9-13

Commutation for an Animal. An animal once vowed is treated as holy; any attempt to substitute another less valuable renders the second holy (and forfeit) also. An unclean animal cannot be directly offered for sacrifice; it must, therefore, be sold and the price paid to the Temple; if the owner wishes to have it back he must pay an extra 20 per cent. (cf. Leviticus 27:15; Leviticus 6:5; Leviticus 22:14).