Is it permissible to build a water fountain (sabil) or perform any other continuous charity (sadaqah jariyah) with the amount allocated for Hajj on behalf of the deceased mother who had not performed Hajj due to ignorance of its obligation, if the amount is insufficient for Hajj and the siblings have disposed of their shares? And are the children sinful if they are unable to perform Hajj on her behalf?

If a person who was able to perform Hajj died without having performed it, and left behind wealth, then the expenses for Hajj must be disbursed from his estate. This debt takes precedence over the division of the inheritance. It is permissible for Hajj to be performed on his behalf from Mecca, even if the deceased was from another country. If the inheritance has been divided and it later becomes clear that the cost of Hajj is greater than what was allocated, then the heirs must complete the additional amount proportionally to their share of the inheritance. If they do not have the money currently, it remains a debt upon them until they are able to repay it.