In mahabharata Arjuna was grieved on the loss of son Abhimanyu in the battle field .This was in his mind after the completion of battle . Lord Krishna wanted to  realise  the reality of life to him . He took Arjuna to heaven where after end of human life there. and showed Arjuna pointing one soul this is the soul of Abhimanyu Arjuna in a haste went to that soul and in a loving voice told I am arjuna your father Immediately that soul retorted who are you I don't know Arjuna was shocked At that time Lord Krishna told him Arjuna the bond is only with the body in the human life .Once soul left the body bond ends there

The lesson is  One human must treat all the human beings with the affection as for as possible and at the same time one must treat their blood ones with care with social oblication