Here the son never did any mistake ...why should a son should suffer for father's karma since he is not the one who did the business?
Dear Vignesh,
Your question is logical and acceptable from a human and mundane point of view. But God is a Just God, who sometimes recompenses the iniquities of the fathers upon the descendants to the 3rd and 4th generation. God's ways are apparently unfathomable, beyond comprehension by humans, beyond grasp of human intelligence and logic.
Yet, God is LOVE personified, He is faithful, He will abundantly pardon, He is of infinite mercy, full of lovingkindness. When we sincerely repent for our iniquities, turn to God for forgiveness, He has already forgiven. To err is human, to forgive divine. Even if you err seven times and all the seven times humble yourself and seek God's forgiveness, He will hasten to forgive you seventy times seven.
You did the right thing by putting God first, turning to God first and then to men to Pray, to intercede. The fervent prayer of a righteous man availeth much. Ask and ye shall receive. On many occasions we do not receive because we do no ask. We do not ask because we apply our own limited intelligence and conclude we are unworthy of God's mercy and pardon. No iniquity is so unworthy that God will not pardon. It is easy to receive answer from God, right to expect God to perform miracles, turn adversity and sorrow into joy but God responds to Faith in Him and not to emotions nor to artificial gestures nor to grand eloquent language. He is nearest to and lives inside a broken heart and in one who is of a contrite spirit.
I appreciate your love for your friend, your empathy for your friend and your appeal to intercede for your friend. Interceding for your friend, sure I will do and you may rest assured, but the only mandate is Faith. For, what things so ever you desire, when you pray, believe that you receive them and you shall have them. In all your ways acknowledge God and lean not on your own understanding. When a prayer/petition is made to God, and made in Faith, you are sure to receive the answer and the answer will be a guidance, an advice on what action to perform. Whatever God (not men) advises, guides, immediately obey, act (and do act) upon it, not doubting, not wavering, not vacillating. Trust in him as a child trusts his/her Father. Your friend's deliverance is imminent, is just a matter time.
May God Bless your friend and you.