Isaac
At Isaac generation no new items are added to Abraham's Covenant. It is, though confirmed as having passed to him.
Confirmed to Isaac
God did not stop at Abraham. The next generation was told the same thing. This time, though, since the covenant was set, there was no need to execute a new covenant. All that remained was reassurance for the people involved that God had a great thing planned.
We see this in Isaac's life in Genesis chapter 26. The following is the relevant text:
Each of the main components of Abraham's covenant are repeated here again. Isaac will now be blessed.(Gen 26:3) Isaac, together with his dependents will receive the land.(Gen 26:3) Isaac will have numerous offspring, as numerous as the stars in the sky.(Gen 26:4) Finally, through his offspring, all nations on earth will be blessed.(Gen 26:4)
The nature of the covenant being made with Abraham, not with Isaac, is reiterated.(Gen 26:5) Isaac is not required to do anything. Because of the covenant that God made with Abraham it is sure to happen. It will happen as surely as God exists. This has less requirement placed on Isaac than even the New Covenant. Isaac does not even need to believe that this will happen, it still will. Those of us, under the New Covenant, are required to believe.
The next generation, Jacob, has the same thing happen. We now turn there.