Covenant of Works Republished at Sinai - Colquhoun

In chapter one of his book, Treatise on the Covenant of Works, John Colquhoun refers to the Sinai covenant as his first proof of the existence of a covenant of works with Adam:

1. This contract between God and the first
Adam, is in sacred writ, expressly styled a covenant.

"These are the two covenants; the one from the
mount Sinai, which gendereth to bondage, which
is Agar." 

Here are two covenants mentioned,
the one of which, genders to bondage, and the
other, to liberty or freedom. The covenant of
grace, or "The law of the Spirit of life in Christ
Jesus," is the one which genders to liberty, or
which makes free from the law of sin and death.
The one, therefore, which genders to bondage,
must be that law or covenant of works, which was
republished to the Israelites, from mount Sinai;
which required perfect obedience to the ten commandments,
on pain of death, and contained a promise
of life, to the man who should do, or perform
such obedience. 

This covenant, which "the thunderings,
and lightnings, and thick cloud, and voice
of the trumpet exceeding loud, on the mount," proclaim
to have been a covenant of works, gendereth
to bondage. By the awful manner, in which it
was then displayed; by the strictness of its precepts,
and the dreadful severity of its penalty, it
tends to beget a slavish and servile spirit, in all
who are under the dominion of it, and to subject
them to bondage of the most ignominious kind. 

Now this covenant, is here contrasted with the covenant
of grace, which, for his comfort, was revealed
to Adam immediately after the fall ; and,
therefore, it must have been made with him, before
the fall. And indeed, we cannot suppose that Jehovah,
to whom infinite Goodness, as well as infinite
Justice, is always essential, could have published
such a covenant of works, from Sinai, to
man in his state of sin, in which he is "without
strength to obey, if he had not already entered
into it with him, in his state of innocence. (pp. 5-6)