Bismillah.
Narrated Abu Humaid Al-Sa'idi (radiallaahu `anhu):
Allah's Apostle (sallallaahu `alayhi wasallam) 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 (sallallaahu `alayhi wasallam) checked the account with him.
So double check whatever it is that you assign to someone. Especially money matters. It's a Sunnah!
Taken from: http://ilookilisten.wordpress.com/2013/01/01/double-checking-is-a-sunnah-hadith-no-1276/
