What the Bible says about Book of the Covenant
(From Forerunner Commentary)
In part, these passages frame the establishment of the Old Covenant. Moses inscribed the words God uttered in a book, the Book of the Covenant, and read them to all the people. Three times (apparently twice before they even heard the words of God) the people asserted that they would do "all the words which the LORD has said" (Exodus 19:8; Exodus 24:3 and 7). Moses confirmed the covenant by an animal sacrifice, sprinkling blood on the people (Exodus 24:5-8).
Charles Whitaker
Searching for Israel (Part Three): The Old Covenant