The ashes of a heifer (Heb. 9: 13), red and without defect (Num. 19: 2), are ordered to be mixed with water for the purification of the priest or of a city (Deut. 21: 1 ff.). The epistle to the Hebrews argues that if the old ritual sacrifices were efficacious, then the sacrifice of Christ must be much more so—indeed of eternal validity.