The Westminster Standards teach that the Covenant given at Sinai was indeed a republication of the Covenant of Works:

"God gave to Adam a law, as a covenant of works, by which He bound him and all his posterity to personal, entire, exact, and perpetual obedience; promised life upon the fulfilling, and threatened death upon the breach of it: and endued him with power and ability to keep it. This law, after his fall, continued to be a perfect rule of righteousness, and, as such, was delivered by God upon Mount Sinai, in ten commandments, and written in two tables: the four first commandments containing our duty towards God; and the other six our duty to man."

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Richard
CofE
UK