But ye are come unto mount Sion…and to Jesus the mediator of the new covenant, and to the blood of sprinkling… – Hebrews 12:22,24

The text does not merely speak of the blood shed but of “the blood of sprinkling.” This is the atonement applied for divine purposes and especially applied to our own hearts and consciences by faith. In the Old Testament the blood of sprinkling meant a great many things; in fact, I cannot just now tell you all that it signified. We meet with it in the Book of Exodus, at the time when the Lord smote all the first-born of Egypt. Then the blood of sprinkling meant preservation. The basin filled with blood was taken, a bunch of hyssop was dipped into it, and the lintel and the two side posts of every house tenanted by Israelites were smeared with the blood, and when God saw the blood upon the house of the Israelite, He bade the destroyer pass that family by and leave their first-born unharmed. The sprinkled blood meant preservation; it was Israel’s Passover and safeguard. The blood of sprinkling means the blood of ratification or confirmation of the covenant, which God has been pleased to make with men in the person of our Lord Jesus Christ. Since Jesus died, the promises are Yes and Amen to all believers and must assuredly be fulfilled. The covenant of grace had but one condition, and that condition Jesus has fulfilled by His death, so that it has now become a covenant of pure and unconditional promise to all the seed. In many cases the sprinkling of the blood meant purification. If a person had been defiled, he could not come into the sanctuary of God without being sprinkled with blood. This sprinkling was used in the case of recovery from infectious disease, such as leprosy; before such persons could mingle in the solemn assemblies, they were sprinkled with the blood and thus were made ceremonially pure. In a higher sense this is the work of the blood of Christ. It preserves us, it ratifies the covenant, and wherever it is applied it makes us pure, for “the blood of Jesus Christ His Son cleanses us from all sin.” We have our hearts sprinkled from an evil conscience, for we have come unto the obedience and sprinkling of the blood of Jesus Christ. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1888.cfm