It burst and he stood outside its pit and he took the cedar wood, hyssop and scarlet wool. Once the cow burst due to the heat of the fire, the priest would take the cedar wood, hyssop and scarlet wool into his hand so that he could throw them into the fire (see Numbers 19:6).
He said to them, "Is this cedarwood? Is this cedarwood?" "Is this hyssop? Is this hyssop?" "Is this scarlet wool? Is this scarlet wool?" Three times he repeated each question and they answered him "Yes, yes" three times to each question. The thrice-repeated formula is meant to give great publicity to the ceremony, as is done with the Omer (barley offering) according to Menahot 10:3. In my opinion this is part of the polemic against the Sadducees (see mishnah 7). The Pharisees/rabbis have to prove that they take this ceremony with utmost gravity in order to balance out their leniency that the red cow ritual can be performed by a priest who is a "tvul yom" someone who has been to the mikveh but has not waited till sundown to become pure.