Is it permissible for a woman who sold a plot of land to a man who died before its registration, to ask for additional money from his heirs, who do not observe prayer, after the land's price has doubled, or must she complete the registration procedures without an increase?

If the sale has met its conditions and pillars, then the seller must hand over the land to the heirs of the deceased buyer. She does not have the right to annul the sale or demand a higher price unless the heirs agree. Registering the sale in official papers is only for documentation and does not affect the validity of the sale. It is recommended for the heirs to agree to annul the sale, based on the hadith: "Whoever annuls a sale for a Muslim, Allah will annul his slip." The fact that the heirs do not pray does not justify annulling the sale, for Allah Almighty says: "O you who have believed, fulfill [all] contracts."