It is permissible for this woman to marry after her husband dies, but she should offer expiation for her oath, because the Prophet (peace and blessings of Allaah be upon him) said: “By Allaah, if Allaah wills, I do not swear an oath then see something better than it but I will offer expiation for my oath and do that which is better.” Narrated by al-Bukhaari, 3133; Muslim, 1649. And he (peace and blessings of Allaah be upon him) said: “If you swear an oath then you see something that is better than it, offer expiation for your oath and do that which is better.”
Narrated by al-Bukhaari, 2622; Muslim, 1652.
Marriage is better for this woman then her remaining unmarried, because that serves many interests.
