Genesis 22 is the story from the Bible of how the Jewish/Christian/Muslim God told Abraham to kill his oldest son as a human sacrifice, then at the last minute (when Isaac was all trussed up on top of the altar) told him he didn't have to do it after all. It wouldn't surprise me if Tolkien had the story in mind when he wrote the original version of this.
Part 23: Genesis 22, the prequel
Next time: Part 24: A small oversight
Chibis by tektek.org