He could reject the promise and go back to Chaldea.
God imputed righteousness, not man. Men break covenants, not God.
Even with all that Abram did, David etc... Paul says this about the imputed Righteousness of God:
Rom 4:1 What then shall we say that Abraham, our ancestor according to the flesh, has discovered regarding this matter?
Rom 4:2 For
if Abraham was declared righteous by the works of the law,
he has something to boast about – but not before God.
Rom 4:3 For what does the scripture say? “
Abraham believed God, and it was credited to him as righteousness.”
Rom 4:4
Now to the one who works,
his pay is not credited due to grace but due to obligation.
Rom 4:5 But to the one who does not work, but believes in the one who declares the ungodly righteous,
his faith is credited as righteousness.
Rom 4:6 So even David himself speaks regarding the
blessedness of the man to whom God credits righteousness apart from works:
Rom 4:7 “Blessed are those whose lawless deeds are forgiven, and whose sins are covered;
Rom 4:8 blessed is the one against
whom the Lord will never count sin.”
What could Abraham, or David, or any other believer do to change this fact that Yahweh Elohim does not take HIS
Imputed Righteousness away once given?
Nothing.
Justification is one time!
God Bless!