In the name of Allah, the Most Gracious, the Most Merciful.
Quran: Chapter 4, ‘Lan Tanalu’ ‘By no means shall you attain’, Sura: 4 ‘An-Nisa’ ‘The Women’, Verse: 22
Verse 22: And marry not women whom your fathers married, except what has already passed; indeed it was shameful and most hateful, and an evil way.
Notes by samia2010oct: Before Islam an extremely shameful culture existed among the people of Makka. After the death of the father his eldest son from his first wife used to marry the father’s youngest wife. This culture is completely stopped, banned and forbidden by Islam.
In Islam all the wives of a father are mothers to all the children of the father no matter what the age of the youngest wife may be. When a father marries a woman no matter what age she is, because of solemnizing marriage to their father, she becomes mother to all the children of her husband. Even after the death of the father all the wives of the father remain wives of the father because the wives have a share in the dead husband’s wealth and assets. The wives are allowed to re-marry after husband’s death but to some other man, other than dead husband’s son. All the wives of the father must be respected by all the children of the father in his life and also after his death.
If a man in today’s world, unknowingly and mistakenly married the widow of his father, he must quickly divorce her as per Islamic rule, with all the benefits given to a divorcee in Islam.
When a person accepts Islam with the change of rules governing his life, he starts enjoying new Islamic life. Whatever sin he committed in his non Islamic life before Islam, he repents it, stops doing it in his Islamic life, compensates for the loss if some one’s right was snatched and asks for forgiveness from Allah the Most Gracious, the Most Merciful. So those sins are forgiven by Allah provided he repents it, stops doing it in his Islamic life, compensates for the loss if some one’s right was snatched and asks for forgiveness from Allah, then the person starts a new life without the burden of before Islam sins.
The same holds true for the born Muslims as well. When they realize their mistake, they stop doing it, repent it, compensate for the loss if some one’s right is snatched and ask for forgiveness from Allah. Allah forgives their sin provided they stop it forever, compensates for the wrong doing and they start a new sinless life according to Islam.
It is Big Sin to marry the wife of one’s dead father. For Big Sins, Gunaahe Kabira, there is the punishment of unbearable burning of whole body by Unending Fire. At this point we also remember that there are many sins for which the punishment is given by Allah in this world too and this sin is one of them.