From Robert Louis Stevenson’s Dr. Jekyll and Mr. Hyde:
“I incline to Cain’s heresy,” he used to say quaintly: “I let my brother go to the devil in his own way.”
I’ve several times used this line – ‘Cain’s heresy’ – at work when people ask about the progression of someone else’s project or their absence in a meeting. Like most of my answers it kills further questioning.