…so much the more also Jesus has become the guarantee of a better covenant. – Hebrews 7:22

The covenant cannot fail because the human side of it has been fulfilled. The human side might be regarded as the weak side of it; but when Jesus became the representative of man that side was sure. He has at this hour fulfilled to the letter every stipulation upon that side of which He was the surety. He has magnified the law and made it honourable by His own obedience to it. He has met the demands of moral government and made amends to holiness for man’s offences. The law is more glorified by His atoning death than it was dishonoured by man’s sin. This Man hath offered one sacrifice for sins for ever, and that is so effectual for the fulfillment of the covenant that He sits down at the right hand of God. Since, then, that side of the covenant has been fulfilled which appertains to man, there remaineth only God’s side of it to be fulfilled, which consists of promises-unconditional promises, full of grace and truth, such as these: -“Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you. A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh. And I will put My spirit within you, and cause you to walk in My statutes, and ye shall keep My judgments, and do them.” Will not God be true to His engagements? Yes, verily. When He makes a covenant, and on man’s part the compact has been fulfilled, depend upon it, on the Lord’s side no word will fall to the ground. Even to the jots and tittles, all shall be carried out. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2108.cfm