Shama-il Tirmidhi Chapter 54, Hadith Number 2 (383).

Abu Hurayrah Radiyallahu ‘Anhu reports that Faatimah (Radiyallahu ‘Anha) came to Abubakr (Siddique Radiyallahu ‘Anhu) and asked him who his heirs were. He replied: ”My wife and children”. (Faatimah Radiyallahu ‘Anha asked:) ”Then why did I not become heir to my fathers estate?” Abubakr (Siddique Radiyallahu ‘Anhu) Said: “I heard the command of Rasulullah Sallallhu ‘Alayhi Wasallam, that we do not leave any heirs. But (I being a guardian of the waqf) for those whom Rasulullah Sallallahu ‘Alayhi Wasallam had decreed a daily allowance, I will continue to grant it. And on whom Rasulullah Sallallahu ‘Alayhi Wasallam used to spend. I will continue to spend”.

Commentary
Apparently it seems Sayyidina Faatimah Radiyallahu ‘Anha thought that being a ruler, the estate of Sayyidina Rasulullah Sallallhu ‘Alayhi Wasallam was not adjudged for his heirs. For this reason she inquired from Sayyidina Abubakr Radiyallahu ‘Anhu that would he have any heirs. Sayyidina Abubakr Radiyallahu ‘Anhu gave a shar’ee reply to the query, otherwise according to his own will he had stipulated that his wealth must be returned to the Baytul Maal (treasury). Therefore Sayyidina Abubakr Radiyallahu ‘Anhu did not leave any heirs for his estate. The saying of Sayyidina Rasulullah Sallallahu ‘Alayhi Wasallam that ‘We do not leave any heirs’ is a well known hadith, which has been mentioned in different wordings. In some narrations only those words are narrated that have been mentioned above. In some narrations, it is stated that, ‘We the group of ambiyaa, do not leave heirs’. Shah Waliyullah has written in his ‘Musawwa) (Commentary on Muwatta) on this subject that Sayyidina Rasulullah Sallallahu ‘Alayhi Wasallam did not leave any heirs, has been narrated by more than ten Sahaabah.