Aside from the first mention of the New Covenant, Jer. 331:31-34, where is the mention of the New Covenant in the *man named( New Testament?
With all due acknowledgment, the blessing given to Abraham first of all, that is the Gospel, has been there for all who believe God ever since, albeit before our blessed Savior came to save us, most were blinded by the veil of Moses or simply knew nothing of the prophets, non Hebrews that is.
"just as Abraham “believed God, and it was accounted to him for righteousness.” 7Therefore know that only those who are of faith are sons of Abraham. 8And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel to Abraham beforehand, saying, “In you all the nations shall be blessed.” 9So then those who are of faith are blessed with believing Abraham."
Abraham believed the Word that came from God = the same Word that was God from the Beginning.
God, Himself, was the first Person to preach the Gospel for HE is the First and the Last.