The bequest to the children of a deceased son in the place of their father

Question:
Honorable Shaykh, a man left a bequest to his heirs and said to them: “If I die, the children of my deceased son will take the place of their father in receiving the inheritance.” Is this bequest permissible? Is it to be taken from one-third of the estate? Or are they to be treated as their father would have been if he were alive? Please give us a ruling, and may Allah reward you. Know that this issue occurs frequently in our society.

Answer:
There is nothing wrong with that, provided that the children who are to receive it are not heirs from their grandfather. If they are included in the general category of heirs, they would be contradicting them, so there is no harm in bequeathing to them because they are not heirs. However, the bequest must be within the limit of one-third or less; it must be within the limit of one-third or less. If their father’s share is less than one-third, then it is less than one-third.