Is the deceased son's wife, with whom her husband had not consummated the marriage, permanently or temporarily forbidden [for marriage]?

If a man marries a woman, this woman becomes permanently forbidden to his father upon the mere conclusion of the marriage contract, regardless of whether consummation occurred or not, and regardless of whether the son divorces her or dies. This is based on Allah Almighty's saying: "And the wives of your sons who are from your own loins." This prohibition includes the son's fathers and his grandfathers from all sides.