Leviticus 14:4-6

New Revised Standard Version Catholic Edition

⁴ the priest shall command that two living clean birds and cedarwood and crimson yarn and hyssop be brought for the one who is to be cleansed. ⁵ The priest shall command that one of the birds be slaughtered over fresh water in an earthen vessel. ⁶ He shall take the living bird with the cedarwood and the crimson yarn and the hyssop, and dip them and the living bird in the blood of the bird that was slaughtered over the fresh water.