In Numbers 19, God gives instructions to Moses about the ashes of the red heifer. Moses is told that the heifer must meet several specifications. First, it to be perfect in that there is no spot or blemish to be found in it. Second, it must not have more than two hairs of any color. Thirdly, it must not have ever had a yoke upon her neck.
Finally, the heifer was to be taken outside of the camp and slaughtered with a knife and its body burned to ashes before the high priest on cedar wood. It was then to be mixed with hyssop, scarlet, and running water to be stored in a stone pot for the purpose of purification; most importantly the purification of the temple, its implements, and priests.
The significance of the red heifer is important today as that before the third temple can be rebuilt as prophesied in Scripture and the priesthood restored, the ashes of the red heifer must be reestablished for the purification of the temple, its implements, and priests.
This is where some disagreement arises. The disagreement is as to whether simply raising another red heifer that meets the specifications is sufficient while others believe that the original ashes from the ninth red heifer from Moses must first be found and added to the new before it is acceptable.
This is exciting as that Jewish tradition teaches that upon the establishment of the tenth red heifer, the Messiah will come!