c. 1200 BCE, Nineteenth Dynasty
The Tale of Two Brothers
A folk tale, not a myth, and the oldest surviving story of a wife falsely accusing a man who refused her.
Two brothers, named Anubis and Bata after gods but not being them, live and farm together. Anubis's wife propositions Bata; he refuses; she accuses him of assault. Anubis waits to kill his brother, who flees and is saved when Ra puts a lake full of crocodiles between them. Bata cuts off his own genitals and throws them in the water to prove his innocence, then tells his brother he is going to the Valley of the Cedar and will place his heart in the blossom of a cedar tree.
From there it becomes stranger. The gods make a wife for Bata; the Pharaoh takes her; she has the tree cut down and Bata dies. Anubis finds the heart and revives him. Bata becomes a bull, is slaughtered, and springs up as two persea trees; those are felled, and a splinter flies into the wife's mouth, so that she conceives him and gives birth to him. He grows up and becomes king.
Where it comes from
Papyrus D'Orbiney
c. 1200 BCE, now in the British Museum, copied by the scribe Ennana. A single manuscript.
What is late, foreign or single-source
Not a myth at all, strictly. It is a literary tale that uses divine names for human characters, and reading it as evidence for the cult of Anubis is a category error. It is included here because it is constantly quoted as Egyptian mythology, and because it is a genuinely good story.
What the story was for
It is the earliest written version of the falsely-accusing-wife motif that later appears as Potiphar's wife in Genesis and as Hippolytus in Greek tragedy, by several centuries. The transformation sequence at the end, heart in a tree to bull to tree to child, is not theology; it is folklore, and it is closer to a European fairy tale than to anything in the funerary texts.
Other myths