in a book
Exodus 17:14
17:14 in a book. This is the first reference to Moses actually writing down the events that were transpiring. There are a number of other such references throughout the last four books of the Pentateuch (e.g., Numbers 33:2). Although this is the first specific command of God to write His words down in a book, there is a much earlier reference to “the book of the generations of Adam” (Genesis 5:1). See also Exodus 24:4; 34:27.