Parah 4:3-4

Parah 4:3

If the red heifer was burned without wood, or with other than the prescribed kind of wood, or even with only straw or stubble, it is valid. If he skinned it and cut it up, it is valid. If he slaughtered it intending to eat its flesh or drink its blood, it is valid. Rabbi Eliezer says that improper intentions don’t invalidate the red heifer.

Parah 4:4

Anyone involved with the cow’s preparation, from start to finish, renders their clothing ritually unclean and renders the cow invalid by performing other work simultaneously. If the cow was invalidated while being slaughtered, it doesn’t render clothing unclean. If it happened while the blood was being sprinkled, all who were involved with it before render their clothing unclean but those who were involved with it after it was invalidated do not render their clothing unclean. We find from this that a stringency leads to a leniency. The red heifer is always subject to the laws of misappropriation. Wood may be added to the fire. The ceremony must be performed by day, by a kohein. Performing other labor while involved with the red heifer renders it invalid. All this only applies until the cow has become ashes. Other labor also invalidates the water until the ashes are put into it.