Genesis 4:9

9 Then the LORD said to Cain, “Where is your brother Abel?” “I don’t know,” he replied. “Am I my brother’s keeper?”

Read Genesis 4:9 Using Other Translations

And the LORD said unto Cain, Where is Abel thy brother? And he said, I know not: Am I my brother's keeper?
Then the LORD said to Cain, "Where is Abel your brother?" He said, "I do not know; am I my brother's keeper?"
Afterward the LORD asked Cain, “Where is your brother? Where is Abel?” “I don’t know,” Cain responded. “Am I my brother’s guardian?”