Hishaam bin ‘Urwah mentions that seven Sahaabah (radhiyallahu ‘anhum) had appointed Hazrat Zubair (radhiyallahu ‘anhu) to be the executor of their estates after their demise.
Among these Sahaabah (radhiyallahu ‘anhum,) were Hazrat ‘Uthmaan (radhiyallahu ‘anhu), Hazrat ‘Abdur Rahmaan bin ‘Auf (radhiyallahu ‘anhu), Hazrat Miqdaad (radhiyallahu ‘anhu) and Hazrat ‘Abdullah bin Mas‘ood (radhiyallahu ‘anhu).
After the demise of these Sahaabah, Hazrat Zubair (radhiyallahu ‘anhu) safeguarded their wealth for their minor children and he would spend on them from his own personal wealth.
(Usdul Ghaabah 2/211)