Then when G-d asks [Cain], ‘Where is your brother Abel?’ he arrogantly responds, ‘I do not know. Am I my brother’s keeper?’
In essence, the entire Bible is written as an affirmative response to this question.
The trees are in their autumn beauty,
The woodland paths are dry,
Under the October twilight the water
Mirrors a still sky;
To think that before the hills were formed, or the channels of the sea were scooped out, God loved me; that from everlasting to everlasting His mercy is upon His people. Is not that a consolation?