Sahih Muslim | Book 19 | Hadith Number 4347

Narrated by Umar
It has been narrated on the authority of Umar, who said: The properties abandoned by Banu Nadir were the ones which Allah bestowed upon His Apostle for which no expedition was undertaken either with cavalry or camelry. These properties were particularly meant for the Holy Prophet (may peace be upon him). He would meet the annual expenditure of his family from the income thereof, and would spend what remained for purchasing horses and weapons as preparation for Jihad.