I incline to Cain's heresy," he used to say quaintly: "I let my brother go to the devil in his own way.

And the LORD said unto Cain, Where is Abel thy brother? And he said, I know not: Am I my brother's keeper? / And he said, What hast thou done? the voice of thy brother's blood crieth unto me from the ground.

Like Cain and Abel, Caesar and Brutus, Jesus and Judas, back stabbers do this

And she again bare his brother Abel. And Abel was a keeper of sheep, but Cain was a tiller of the ground.

And Cain told Abel his brother. And it came about when they were in the field, that Cain rose up against Abel his brother and killed him. Then the Lord said to Cain, 'Where is Abel your brother?' And he said, 'I do not know. Am I my brother's keeper?' And He said, 'What have you done? The voice of your brother's blood is crying to Me from the ground.' Genesis 4:9-11

And Cain talked with Abel his brother: and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him.