´It was narrated from Hisham bin 'Urwah, from his father, from 'Abdullah bin Az-Zubair, that the Messenger of Allah said:` "Any man who gives a lifelong gift to another man, it belongs to him (the recipient) and to his descendants, and to those who inherit from him."
Hadith Referenceسنن نسائي / كتاب العمرى / 3774
Hadith Gradingالألبانی:صحيح الإسناد | زبیر علی زئی:إسناده حسن
Even if he does not say it for his children, that thing will still be inherited by the children as inheritance. This has been explicitly stated in the previous ahadith.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 3774