Keeping a deceased's vow that was not kept during his lifetime

Q: A man married more than one wife, but none of them gave birth to any children. The man was anxious to have children, so he vowed that he would slaughter an adult camel for each child that Allah may grant him. Allah blessed him with fifteen children, nine boys and six girls. To keep his vow, the man slaughtered five adult camels, but he was unable to slaughter the rest. The man died, but before his death, he told people that he had vowed to slaughter the camels for every boy, not girl, that he was granted. He left a small amount of money and now his sons want to keep his vow. Your Eminence, we would like to know what your advice is on this matter. Is it permissible to slaughter the young camels, which are more available in the market nowadays, due to the lack of adult camels? If it is permissible for us to slaughter young camels, how should they be slaughtered and distributed? It should be noted that `Alyan `Aly Al-Mutiry, who made this vow, is now dead and his heirs mention that he only left a modest house. He also did not give one-third of his wealth to charity, because he died suddenly and his last words were not clear. His house was sold for 60,000, but the heirs have not yet been given their shares of the estate. The questioner mentions that adult camels are not sold for slaughter now, but are sold for their milk instead and are very expensive. The seven boys and five girls that he left would like Your Eminence to reply them in writing. May Allah protect you.

A: Firstly, if the reality is as you mentioned, that your father vowed to slaughter some camels and could not slaughter them all, then you, as his children, should slaughter the remaining adult camels (Part No. 16; Page No. 285) that he vowed to slaughter from the money raised from the sale of the house. But if that is not enough, then the sons, being eager to keep their father's vow, should slaughter, as many as they can from the other adult camels, because Allah (Exalted be He) says: So keep your duty to Allâh and fear Him as much as you can Secondly: If your father died without bequeathing one-third of his wealth to charity, you do not have to give one-third of his wealth to charity. It is recommended that you do good for your father after his death, by giving charity in his behalf and supplicating to Allah to have mercy on him and to forgive him. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.