Bede, on Num 19:2

“This is the observance of the victim, which the Lord hath ordained. Command the children of Israel, that they bring unto thee a red cow of full age, in which there is no blemish, and which hath not carried the yoke:”

“Now [Moses] declares that the ashes of the victims (which ought to be taken as a great mystery) are "the sprinkled ashes of a red heifer," which (as the apostle also bears witness) sanctified "those who have been defiled, so that [their] flesh is made clean." He also understands that the sacrament of the Lord's passion, which saves us by purifying us forever, is prefigured in these ashes. Thus the burning of a red heifer designates the actual time and event of Christ's passion, and the burnt ashes which were kept for the cleansing of those who were unclean suggest the mystery of that same passion which has already been completed, by which we are daily purged from our sins.”

Imported from an open dataset — not yet checked against the printed edition.