Hebrews 10:2

else they would have discontinued to make the offering, because they who performed the service being once made clean, would have had no more sense of sins on their conscience.

Hebrews 9:13-14

For if the blood of bulls, and of goats, and the ashes of an heifer sprinkling the defiled sanctifieth to corporal purification,

Hebrews 10:17

[he adds,] "and their sins and their iniquities I will in no wise remember any 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
[he adds,] "and their sins and their iniquities I will in no wise remember any more."
Hebrews 9:13
For if the blood of bulls, and of goats, and the ashes of an heifer sprinkling the defiled sanctifieth to corporal purification,

General references

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