Hebrews 9:7

but into the second once a year only the chief priest [enters], not without blood, which he offers for his errors and those of the people,

Hebrews 9:25

not that he may often present himself, as the chief priest enters into the sanctuary once a year with the blood of another [being];

Hebrews 10:3

But in them there was a remembrance of sins, year by year;

Hebrews 10:14

For by one offering he has perfected forever the sanctified.

Treasury of Scripture Knowledge

Summary

And this shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year. And he did as the LORD commanded Moses.

Bible References

Once a year

Hebrews 9:7
but into the second once a year only the chief priest [enters], not without blood, which he offers for his errors and those of the people,
Hebrews 10:3
But in them there was a remembrance of sins, year by year;