Sahih Bukhari Volume 002, Book 024, Hadith Number 576.

Narated By Abu Humaid Al-Sa'idi : Allah's Apostle (p.b.u.h) appointed a man called Ibn Al-Lutbiya, from the tribe of Al-Asd to collect Zakat from Bani Sulaim. When he returned, (after collecting the Zakat) the Prophet checked the account with him.