Hasan and Sa'id bin al-Musayyib, may Allah have mercy on them, said: If a man says, "My sword is for such-and-such person, and if he dies, then for such-and-such person, and if he also dies, then it will return to me," both said: It will be for the first person. And Humayd bin 'Abd al-Rahman said: It will be carried out just as it was bequeathed.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3297
Hisham bin Urwah narrated that Urwah said: If a man gives a gift to another man and says: "This is for you, and if you die, then for so-and-so, and if that person also dies, then for so-and-so, and if he also dies, then it will return to me." Urwah said: The bequest will be executed as stated, even if there are a hundred people.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3298