Not permissible to delay Zakah payment for sister's future marriage

Assalamualaikum, We a have case in our family for which Fatwa is required. A father had left behind 2 waives. Children of 1st wife are grown up and earning. Children of 2nd wife (2 son &1 daughter ) are studying. At present Children of 1st wife are taking care of the expenses of their fathers 2nd wife and their children. As in India lot of money is required for the marrage of Daughter. Hence their relatives are advising the children of 1st wife to keep or deposit the Zakat money for their fathers 2nd wife daughters marrage. Islamic wise is it allowed for 1st wife children to keep the zakat money for the marrage of their fathers 2nd wife daughter . or it is advisable to divide the zakat money into 2 half. One half for poor and 2nd half for the marrage of their fathers 2nd wife daughter . Please advise

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad , is His slave and Messenger.

Whenever Zakah becomes obligatory with respect to a person's property, he is obliged to pay it immediately and it is not permissible for him to keep it to give it to his sister when she needs it; because paying the Zakah is an immediate obligation.

Ibn Qudaamah said: "The Zakah must be paid immediately, and it is not permissible to delay paying it when one is able to do so if he does not fear any harm; this is the view of Ash-Shaafi‘i …. Al-Athram said: I heard Abu ‘Abdullaah being asked about a man, a whole lunar year hád elapsed on his wealth but he delayed paying the Zakah on time. He said: No, he should not delay paying the Zakah, and he emphasized that it should be paid. It was said: he began to give out the Zakah, and he started giving it out gradually. He said: No, he must give out the Zakah entirely when a whole lunar year elapses."

Ad-Dusooqi, from the Maaliki School of jurisprudence, said in his Haashiyah (commentary): "It is obligatory to pay out the Zakah immediately to its eligible recipients; as regards keeping it with him (the payer of Zakah) and every time a person comes to him, he gives him something from it, then this is not permissible."

If the sister is among the people who are eligible to receive Zakah, it is permissible for her brother to pay the Zakah of his money to her if it is not incumbent on him to provide her maintenance needs. If it is incumbent on him to provide her maintenance needs, then it is not permissible for him to pay the Zakah to her based on her being poor, as by doing so, he is evading the obligatory financial support. A brother is obliged to financially support his sister if he is an heir to her (in case she dies) and he has a surplus after providing for his needs and those of his wife and his children.

Some scholars are of the view that the brother is not obliged to financially support his sister, even if he is an heir to her. According to this view, it is permissible to pay the Zakah to her, but as we have already mentioned, it is not permissible for him to save the Zakah and delay paying it to hand it over to her when she needs it.

Allaah Knows best.