Hebrews 10:2

Otherwise would they not have ceased to be offered? Because the worshipers, having been once purged, would have had no more consciousness of sins.

Hebrews 9:13-14

For if the blood of bulls and goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:

Hebrews 10:17

And their sins, and their iniquities will I remember no more.

Treasury of Scripture Knowledge

Summary

For then would they not have ceased to be offered? because that the worshippers once purged should have had no more conscience of sins.

General references

Bible References

Once

Hebrews 10:17
And their sins, and their iniquities will I remember no more.
Hebrews 9:13
For if the blood of bulls and goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:

General references

Hebrews 10:18
Now where remission of these is, there is no more offering for sin.