Found it!

I've been looking for some time now for work by Jonathan Edwards which really helped me know better what God has done in Christ. It is recorded by Conrad Cherry in his book "the theology of Jonathan Edwards". The work in quotes is Edwards... everything else is Cherry:

God is indebted to man and man may demand his salvation from God as a debt. It is clear that on this level, however, Edwards intends in no way to surrendour his position on the debt idea considered on the first level. In the sermon on the soverignty of God in salvation, immediately prior to his point that the believer may demand his salvation from God "as a debt," Edwards avers that "those who are in a state of salvation are to attribute it to sovereign grace alone, and to give all praise to him who maketh them to differ from others. Godliness is no cause for glorying, except it be in God." The possibilty of the believer's demanding salvation on the basis of his own godliness is precluded. But Edwards proceeds in the same sermon to suggest the manner in which salvation may be demanded as a debt by the believer:

"We learn what cause we have to admire the grace of God, that he should condescend to become bound to us by covenant; that he, who is naturally supreme in his dominion over us, who is our absolute proprietor, and may do with us as he pleases, and is under no obligation to us; that he should, as it were, relenquish his sovereign freedom, and should cease to be merely arbitrary in his dispensations towards believers, when once they have believed in Christ, and should, for their more abundant consolation, become bound. So that they can challenge salvation of this Sovereign; they can demand it through Christ, as a debt."

Man does not "tie up" God, but God ties himself to man in the covenant. This is Edwards' interpretation of the Incarnation: God binds himself in covenant with the sinner, and in so doing God freely limits his freedom for man. The sinner-believer demands salvation through Christ, on the ground of Gid's binding himself in Christ, and never through or on the basis of his own goodness or obedience. The demand is solely possible through the union a man has with Christ, who is God's covenant-event in history. The other sermon we cited which openly embraces the debt idea stresses the same fundamental points; the initiative of God in establishing the covenant; and the right of man's claim on salvation through Christ only:

"Salvation is an absolute debt to the believer from God, so that he may, in justice, demand it, on account of what his surety has done. For Christ has satisfied justice fully for his sin; so that it is but a thing that may be challenged, that God should now release the believer from punishment."

...for the elect believer God is no longer the distant, arbitrary ruler; he is the God who has "indebted" himself to man through the Christ, and man may now demand his salvation as God's part of the covenant.

We are needed in glory!