"Am I my brother's keeper?" is a saying from the Bible. It comes from the story of Cain and Abel. [1] After Cain murdered his brother Abel, God asked him where his brother was, and Cain answered: "I know not; am I my brother's keeper?" [2] This quote entered the English language through William Tyndale and his translation of the Bible into English. [3]
The phrase and story is used in Judaism and Christianity. [lower-alpha 1] It shows not only Cain's wrongness in not looking after his brother's well-being, but his hiding of the crime of fratricide. [5]