Jesus did not abolish the Old Covenant/Testament. He fulfilled it.[Matthew 5:17]
The TEN Commandments ARE the Old Covenant the New Covenant replaced them.
In Exodus 34:28 we read: “And He (God) wrote upon the tables the words of the covenant, the Ten Commandments.”
Deuteronomy 4:13: “And He declared unto you His covenant, which He commanded you to perform, even the Ten Commandments.”
Deuteronomy 9:9: “When I was gone up into the mount to receive the tables of stone, even the tables of the covenant.”
Deuteronomy 9:15: “So I turned and came down from the mount . . . and the two tables of the covenant were in my two hands.”
And so on...................
And Jeremiah and Hebrews say Christ replaced the Old Covenant with the New.
““Indeed, a time is coming,” says the Lord, “when I will make a new covenant with the people of Israel and Judah. It will not be like the old covenant that I made with their ancestors when I delivered them from Egypt. For they violated that covenant, even though I was like a faithful husband to them,” says the Lord. “But I will make a new covenant with the whole nation of Israel after I plant them back in the land,” says the Lord. “I will put my law within them and write it on their hearts and minds. I will be their God and they will be my people.” (Jeremiah 31:31–33) (NET)
“For if that first covenant had been faultless, no one would have looked for a second one. But showing its fault, God says to them, “Look, the days are coming, says the Lord, when I will complete a new covenant with the house of Israel and with the house of Judah. “It will not be like the covenant that I made with their fathers, on the day when I took them by the hand to lead them out of Egypt, because they did not continue in my covenant and I had no regard for them, says the Lord. “For this is the covenant that I will establish with the house of Israel after those days, says the Lord. I will put my laws in their minds and I will inscribe them on their hearts. And I will be their God and they will be my people. “And there will be no need at all for each one to teach his countryman or each one to teach his brother saying, ‘Know the Lord,’ since they will all know me, from the least to the greatest. “For I will be merciful toward their evil deeds, and their sins I will remember no longer.” When he speaks of a new covenant, he makes the first obsolete. Now what is growing obsolete and aging is about to disappear.” (Hebrews 8:7–13) (NET)
So, Jesus fulfilled the Ten Commandments on the cross by fulfilling the Two Great Commandments. Remember the Ten HUNG from the Two.
“Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments
hang all the law and the prophets.” (Matthew 22:37–40) (KJV 1900)
You could never fulfill the two by fulfilling the Ten. If so, salvation would have been by Law and not grace. But you always fulfill the Ten if you fulfill the two. It's about motive. The Two = love for God and man. The Ten = doing good things reluctantly with a corrupt motive.