Thomas Boston in his notes to the classic The Marrow of Modern Divinity Edward regarding the republication of the Covenant of works at Sinai,
The Role of Law in the Covenant of Works
“It was not set up by itself as an entire rule of righteousness, to which alone they were to look who desired righteousness and salvation, as it was in the case of upright Adam, ‘For no man, since the fall, can attain to righteousness and life by the moral law’ (WLC 94). But it was added to the covenant of grace, that by looking at it men might see what of righteousness it is by which they can be justified in the sight of God; and that by means thereof, finding themselves destitute of that righteousness, they might be moved to embrace the covenant of grace, in which that righteousness is held forth to be received by Faith.” (79)
Also see here.
There are strong connections between doctrines clearly found in Scripture: the covenant of works (law) and covenant of grace (gospel), the law and Gospel distinction, Adamic Covenant, and Active obedience of Christ to Justification. The Marrow of Modern Divinity is a crucial book that is becoming, to me, a gem above all gems.