Wills are of great antiquity. According to Moslem tradition, Adam(the original, as distinguished from the Old) drafted a will which was handed down orally until reduced to writing in the time of Mahomet. Medieval scholars seriously debated whether this will existed. However, "the authenticity of this will has not been established." If written after Adam's eviction from the Garden of Eden for breach of a substantial condition of the tenancy, it would presumably be a testament only, Adam no longer having any interest in land to transmit.
Elmer M. Million,
Humor in or of Wills,
11 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol11/iss3/4