Tertullian

For in the beginning of the world He gave to Adam himself and Eve a law, that they were not to eat of the fruit of the tree planted in the midst of paradise; but that, if they did contrariwise, by death they were to die. Which law had continued enough for them, had it been kept. For in this law given to Adam we recognise in embryo all the precepts which afterwards sprouted forth when given through Moses; that is, You shall love the Lord your God from your whole heart and out of your whole soul; You shall love your neighbour as yourself; You shall not kill; You shall not commit adultery; You shall not steal; False witness you shall not utter; Honour your father and mother; and, That which is another's, shall you not covet. For the primordial law was given to Adam and Eve in paradise, as the womb of all the precepts of God. In short, if they had loved the Lord their God, they would not have contravened His precept; if they had habitually loved their neighbour—that is, themselves—they would not have believed the persuasion of the serpent, and thus would not have committed murder upon themselves, by falling from immortality, by contravening God's precept; from theft also they would have abstained, if they had not stealthily tasted of the fruit of the tree, nor had been anxious to skulk beneath a tree to escape the view of the Lord their God; nor would they have been made partners with the falsehood-asseverating devil, by believing him that they would be "like God;" and thus they would not have offended God either, as their Father, who had fashioned them from clay of the earth, as out of the womb of a mother; if they had not coveted another's, they would not have tasted of the unlawful fruit.
Therefore, in this general and primordial law of God, the observance of which, in the case of the tree's fruit, He had sanctioned, we recognise enclosed all the precepts specially of the posterior Law, which germinated when disclosed at their proper times. For the subsequent superinduction of a law is the work of the same Being who had before premised a precept; since it is His province withal subsequently to train, who had before resolved to form, righteous creatures. [Answer to the Jews 2]