משנה על במדבר 18:15

Rabbi Joshua and Rabbi Zadok testified concerning the redemption (lamb) of a firstborn donkey, that if it died, the priest receives nothing, Whereas Rabbi Eliezer says: the owner must bear the responsibility as with the five selas [in the case] of a [firstborn] son. But the Sages say: he bears no responsibility any more than in the case of the redemption of second tithes.