Expositor's Bible Commentary Commentary Hebrews 9:19

"For when every commandment had been spoken by Moses unto all the people according to the law, he took the blood of the calves and the goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people," — Hebrews 9:19 (ASV)

When the first covenant was made (Exodus 24), Moses did two things. First, he “proclaimed every commandment of the law to all the people.” That is to say, he set out the terms and conditions of the covenant; he explained the requirements the covenant laid on the people, so they were left in no doubt as to what covenant membership demanded of them. Since they were now God’s people, they had to obey God’s laws.

Second, Moses performed certain ritual actions. In what follows the author includes some details not mentioned in Ex 24. There Moses threw blood on the altar and on the people and read the book to the people. But there is no mention of the water, scarlet wool, hyssop, or the sprinkling of the book. Water, scarlet cloth, and hyssop were used in the rite of cleansing healed lepers (Leviticus 14:4–6; cf. 49–51). Hyssop is mentioned also in connection with the Passover (Exodus 12:22) and the cleansing rites associated with the ashes of the red heifer (Numbers 19:6, 18). The sprinkled book was written by humans, and thus it had to be cleansed of any defilement conveyed to it.