Leviticus 14:4-6

4then shall the priest command to take for him that is to be cleansed two clean living birds, and cedar-wood, and scarlet, and hyssop.

5And the priest shall command that one bird be killed in an earthen vessel over running water:

6as to the living bird — he shall take it, and the cedar-wood, and the scarlet, and the hyssop, and dip them and the living bird in the blood of the bird that was killed over the running water;