'Aayeshah Radiyallahu 'Anha says that Rasulullah Sallallhu 'Alayhi Wasallam said:
"We have no heirs. What we (the ambiyaa) leave is sadaqah" (PT)
English reference (PT): Book 54, Hadith 385 (PT)
Arabic reference (PT): Book 55, Hadith 402 (PT)