Musannaf Ibn Abi Shayba 28:451

Ibn ‘Uyaynah narrated to us, from ‘Amr ibn Dinar, from al-Zuhri, from Malik ibn Aws ibn al-Hadathan, from ‘Umar, who said: The properties of the client of Banu al-Nadir were among what Allah bestowed upon His Messenger as spoils, for which the Muslims did not urge on any horse or camel. Thus, it was exclusively for the Prophet, may Allah bless him and grant him peace. He would withhold from it the expenditure for a year, and whatever remained, he would place it into horses and weapons as equipment in the way of Allah.