Have you ever even read the new covenant?
33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the Lord, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the Lord: for they shall all know me, from the least of them unto the greatest of them, saith the Lord: for I will forgive their iniquity, and I will remember their sin no more.
He says he will put his LAW on our heart of flesh instead of stone tablets.
As far as "the work of Israel being finished"
Jeremiah 31: 35-37
35 Thus saith the Lord, which giveth the sun for a light by day, and the ordinances of the moon and of the stars for a light by night, which divideth the sea when the waves thereof roar; The Lord of hosts is his name:
36. If those ordinances depart from before me, saith the Lord, then the seed of Israel also shall cease from being a nation before me for ever.
37 Thus saith the Lord; If heaven above can be measured, and the foundations of the earth searched out beneath, I will also cast off all the seed of Israel for all that they have done, saith the Lord.