Albert Barnes Commentary Hebrews 9:13

"For if the blood of goats and bulls, and the ashes of a heifer sprinkling them that have been defiled, sanctify unto the cleanness of the flesh:" — Hebrews 9:13 (ASV)

For if the blood of bulls and of goats. Referring still to the great day of atonement, when the offering made was the sacrifice of a bullock and a goat.

And the ashes of an heifer. For an account of this, see Numbers 19:2-10. In Numbers 19:9 it is said that the ashes of the heifer, after it was burned, should be kept for a water of separation; it is a purification for sin. That is, the ashes were to be carefully preserved and, being mixed with water, were sprinkled on those who were for any cause ceremonially impure.

The reason for this appears to have been that the heifer was considered a sacrifice whose blood had been offered, and the application of the ashes to which she had been burned was regarded as evidence of participation in that sacrifice.

It was necessary, where the laws were so numerous respecting ceremonial pollutions, or where members of the Jewish community were so frequently regarded as unclean from contact with dead bodies and in various other ways, that there should be some method by which they could be declared cleansed from their uncleanness.

The nature of these institutions also required that this cleansing should be in connection with sacrifice. To achieve this, it was arranged that there should be this permanent sacrifice—the ashes of the sacrificed heifer—which they could use at any time, without the expense and delay of making a bloody offering specifically for the occasion.

It was, therefore, a provision of convenience and, at the same time, was designed to maintain the idea that all purification was somehow connected with the shedding of blood.

Sprinkling the unclean. Mingled with water, and sprinkled on the unclean. The word unclean here refers to those who had been defiled by contact with dead bodies, or when one had died in the family, etc. See Numbers 19:11-22.

Sanctifieth to the purifying of the flesh. This makes holy as far as the flesh or body is concerned. The uncleanness referred to here related to the body only, and, of course, the means of cleansing extended only to that.

It was not designed to give peace to the conscience or to expiate moral offenses. The offering thus made removed the obstructions to the worship of God, allowing the one who had been defiled to approach Him in a regular manner.

This much the apostle allows was accomplished by the Jewish rites. They had an efficacy in removing ceremonial uncleanness and in making it proper for the one who had been polluted to be permitted again to approach and worship God.

The apostle goes on to argue that if they had such an efficacy, it was fair to presume that the blood of Christ would have far greater efficacy, reaching to the conscience itself and making it pure.