Exodus 22:29-31

29— Thou shalt not delay the fulness of thy [threshing-floor] and the outflow of thy [winepress]. The firstborn of thy sons shalt thou give unto me. 30Likewise shalt thou do with thy calf, with thy sheep: seven days shall it be with its dam; on the eighth day thou shalt give it me. 31— And ye shall be holy men unto me; and ye shall not eat flesh torn in the field: ye shall cast it to the dog.