James Bradford Pate wrote, I found only two places that address the issue explicitly. The first is Irenaeus’ Against Heresies 5.23, and the second is the section on Procilla in Methodius’ Banquet of the Ten Virgins. Irenaeus, who dates to the third century C.E., simply says that Eve was relaying God’s command to the serpent. There is no hint there that Irenaeus thought that Eve was adding to God’s command. Methodius, who dates to the third-fourth centuries C.E., says that Adam received the command not to touch the Tree of Knowledge. Irenaeus and Methodius, like that passage from the Sibylline Oracles, hold that the prohibition on touching the tree actually came from God, and, according to this interpretation, that would mean that Eve was not adding to God’s word.
On the other hand, the rabbinic sources were critical of Eve for adding to God’s commandment, whereas the ancient Christian sources tended to say that Eve got God’s commandment right. A lot of the rabbis were for adding a fence around the law, yet rabbinic literature largely appears to disapprove of what Eve said to the serpent about God’s command. And evangelical critics of Eve, when they criticize Eve, are probably also taking a swipe at the Pharisees and rabbinic Judaism (at least by implication), making a point of “You see what happens when people add commands to God’s word and make God seem stricter than he truly is?”
At the point Eve was having the conversation with the serpent, sin had not yet enter the world. So, it is difficult to believe that Eve added her own words to God’s words. The Plain Word agrees with the ancient Christian sources on this point.