Hebrews 1:3

This Son expresses the radiance of God's splendor and represents His very Being, and He sustains everything by His powerful word. After He had provided cleansing for [man's] sins, He sat down at the right side of the Majesty [i.e., God] on high [i.e., in heaven].

Hebrews 9:7

But [only] once a year the head priest goes alone into the inner room [i.e., Holy of Holies], and never without [animal] blood, which he offers [as a sacrifice] for himself and for the sins done in ignorance by the people.

Hebrews 9:22-23

And, according to the law of Moses, almost everything is [ceremonially] cleansed by blood, for there is no forgiveness [of sins] apart from the shedding of blood.

Hebrews 9:25

Nor was it necessary for Him to offer Himself [to God] often, like the head priest does, who enters the Holy of Holies year after year with blood that belongs to others [i.e., the blood of animal sacrifices].

Treasury of Scripture Knowledge

Summary

And Aaron shall make an atonement upon the horns of it once in a year with the blood of the sin offering of atonements: once in the year shall he make atonement upon it throughout your generations: it is most holy unto the LORD.

Bible References

Aaron

Hebrews 1:3
This Son expresses the radiance of God's splendor and represents His very Being, and He sustains everything by His powerful word. After He had provided cleansing for [man's] sins, He sat down at the right side of the Majesty [i.e., God] on high [i.e., in heaven].
Hebrews 9:7
But [only] once a year the head priest goes alone into the inner room [i.e., Holy of Holies], and never without [animal] blood, which he offers [as a sacrifice] for himself and for the sins done in ignorance by the people.