Awza'i says that Zuhri was asked about a woman who had made a will to give one third of her wealth to her husband in the way of Allah. He replied that this will is not permissible, except in the case where she says that this wealth is to be given to my husband to spend in the way of Allah, and he may spend it wherever he wishes.

Ibn ‘Ulayyah narrates: I was with Dawud bin Abi Hind when two or more men from the family of Hazrat Anas bin Malik (may Allah be pleased with him) came, among whom was also Hazrat ‘Ubaidullah bin Abi Bakr, and they brought with them a letter inside a document, and they said that this was the will of Hazrat Anas bin Malik (may Allah be pleased with him). I opened it and it was written in it:“In the name of Allah, the Most Gracious, the Most Merciful: This is the mention of the will which Anas bin Malik (may Allah be pleased with him) wrote in this document. I advise all my family members to fear Allah, the Exalted and Glorious, to be grateful to Him, to hold firmly to His rope, and to believe in His promise. I advise them to live together in a good manner, to maintain ties of kinship with one another, to do good to others, and to keep fearing Allah. Then he willed that one third of his wealth is to be given in charity, unless he changes his will before his death, from which one thousand (is to be given) to the warriors in the path of Allah, if at that time the unity of the Ummah is not disrupted, and (the rest is) for freeing slaves and distributing among relatives. And my slaves whom I have set free after me, and the time of their freedom has come, then one third of my will shall be responsible for them, in such a way that no hardship or dispute arises.”