Reference for Parah 4:3

שְׂרָפָהּ שֶׁלֹּא בְעֵצִים, אוֹ בְכָל עֵצִים, אֲפִלּוּ בְקַשׁ אוֹ בִגְבָבָה, כְּשֵׁרָה. הִפְשִׁיטָהּ וְנִתְּחָהּ, כְּשֵׁרָה. שְׁחָטָהּ עַל מְנָת לֶאֱכֹל מִבְּשָׂרָהּ וְלִשְׁתּוֹת מִדָּמָהּ, כְּשֵׁרָה. רַבִּי אֱלִיעֶזֶר אוֹמֵר, אֵין מַחֲשָׁבָה פוֹסֶלֶת בַּפָּרָה:

If it was burned without wood, or with any wood, even with straw or twigs, it is valid. If it was skinned and cut up, it is valid. If it was killed with intention to eat from its flesh or to drink from its blood, it is valid. Rabbi Eliezer says: Thoughts do not invalidate with a [red] heifer.

Jastrow