Parah, Chapter 4, Mishnah 3. This chapter walks through the service of the parah adumah and asks, step by step, which deviations ruin it and which the Torah tolerates. Our mishnah takes up three such questions: what may be used as fuel, whether the cow must go into the fire intact, and whether a wrong thought in the mind of the kohein can disqualify the parah the way it disqualifies a korban.
Burning it without wood
"Serafah shelo be'eitzim, o bechol eitzim, afilu bekash o begavava, kesheirah." If he burned the cow with no wood at all, setting the flame directly to the body of the animal, or if he used wood of any sort whatsoever, and even if he used straw or stubble as his fuel, the parah is fit.
The reason lies in the wording of the Torah itself. Scripture does not command that the cow be burned upon wood of a particular kind, nor does it require wood at all. It says simply that it shall be burned, and leaves the manner of the burning unspecified. Where the Torah did not restrict, we do not restrict.
Flaying and cutting it up
"Hifshitah venitchah, kesheirah." If, after the slaughtering, he removed the hide of the parah and cut the animal into pieces, and only then placed it on the fire, the parah remains fit.
This is a concession rather than an ideal. Properly, the parah is meant to be burned whole, hide and flesh and all together, exactly as the Torah describes. But if the kohein flayed it and dismembered it first, the burning still counts and the ashes are valid.
Intention that does not disqualify
A third case turns on what was in the kohein's mind. "Shechatah al menas," he performed the shechitah with a plan in view: "le'echol mibesarah," that he would eat of its meat, "velishtos midamah," and that he would drink of its blood. The mishnah rules "kesheirah," the cow is valid, and the service goes forward as though no such thought had crossed his mind.
The principle is drawn from the laws of korbanos. When a person performs one of the avodos of an offering while intending to eat it beyond its permitted time or outside its permitted place, that thought can render the korban unfit. But this applies only to what is normally eaten. An intention concerning something that is not an object of eating at all does not carry that force. The blood is not food, and the flesh of the parah is not something anyone eats. Such thoughts, therefore, leave the parah as it was.
Intention that does disqualify
Not every stray thought is harmless. If, while slaughtering the parah or while receiving its blood, he intended to sprinkle that blood on the following day, the parah is unfit. Here the intention concerns the avodah itself, done at the wrong time, and the parah is treated exactly as a korban would be treated in the same case. The reason is that the Torah calls the parah adumah a chatas, a sin offering, and that title draws it into the laws of kodashim.
The view of Rabbi Eliezer
"Rabbi Eliezer omeir, ein machashavah poseles baparah." Rabbi Eliezer holds that intention has no disqualifying power over the parah at all. Even if the kohein slaughtered the cow or received its blood while planning to sprinkle that blood the next day, the parah stays fit in his opinion.
Rabbi Eliezer is consistent with his broader position: the parah adumah is not folded into the laws of kodashim, because its entire service is carried out outside the Sanctuary. What governs offerings brought in the Mikdash does not govern a rite performed beyond it, and so the mental disqualifications of korbanos have no place here.