Zaid bin Thabit said: The children of sons are in the position of sons. If the deceased has no son, then the grandsons will be like sons and the granddaughters like daughters. They will inherit in the same way as sons and daughters inherit, and because of them, many relatives will be deprived of inheritance just as they are deprived in the presence of sons and daughters. However, if a son is present, the grandson will not receive anything from the inheritance.

Narrated Ibn `Abbas: Allah's Apostle said, "Give the Fara'id (shares prescribed in the Qur'an) to those who are entitled to receive it; and whatever remains, should be given to the closest male relative of the deceased.'