Is the act of taking one-third of the deceased's estate, placing it in an endowment (waqf), renting it out, then allocating the annual sacrificial animal (Uḍḥiyah) from its income, and distributing the remainder to the heirs with the male receiving the share of two females, considered a correct execution of his will regarding one-third of his wealth for a sacrificial animal? And does the wife have a share in this endowment, or not? What is the solution if the execution was incorrect, and more than 15 years have passed since then?

The will must be executed as it is, and it is forbidden to alter it unless it is for a benefit, for Allah Almighty says: ﴿But whoever alters it after he has heard it – the sin is only upon those who alter it. Indeed, Allah is Hearing and Knowing.﴾ [Al-Baqarah: 181]. However, if altering it leads to something better than what the testator willed, such as making it an endowment (waqf), developing it, and taking from its proceeds what is needed to execute the will, then this is permissible. And whatever is surplus from the proceeds of the endowment remains a will like its origin, to be spent on what the will was intended for, such as sacrifices. What you are doing by distributing the surplus to the heirs or some of them is not permissible, and you must consult the Sharia court regarding this will.