Genesis 4:9

New English Translation

⁹Then the Lord said to Cain, “Where is your brother Abel?”^[a] And he replied, “I don’t know! Am I my brother’s guardian?”^[b]

Genesis 4:9 sn Where is Abel your brother? Again the Lord confronts a guilty sinner with a rhetorical question (see Gen 3:9-13), asking for an explanation of what has happened.
Genesis 4:9 tn Heb “The one guarding my brother [am] I?”sn Am I my brother’s guardian? Cain lies and then responds with a defiant rhetorical question of his own in which he repudiates any responsibility for his brother. But his question is ironic, for he is responsible for his brother’s fate, especially if he wanted to kill him. See P. A. Riemann, “Am I My Brother’s Keeper?” Int 24 (1970): 482-91.

New English Translation (NET)