Theodoret of Cyrus
God instructed that by mixing these ashes with water, those who came into contact with the deceased, touched the bones, or were contaminated in a similar manner should be purified. It is written: ‘And the man, if he defile himself ..., that soul shall be consumed from the midst of the host ...: as the water of sprinkling shall not be sprinkled upon him.’ Likewise, the Lord proclaimed in the sacred Gospel: ‘Except a man be born of water and spirit, he cannot enter into the kingdom of God’ (John 3:5).