Amro bin Shu’aib narrated on the authority of his father who reported on the authority of his grandfather, on the authority of Abdullah bin 'Amro(RAA) that the Messenger of Allah ( صلی اللہ علیہ وسلم ) said:“One who becomes the guardian of an orphan, who owns property, must trade on his behalf and not leave it (saved and unused) until it is all eaten up by Zakah (which is paid yearly).”Related by At-Tirmidhi and Ad-Daraqutni with a weak chain of narrators. And it has a Shahid (supporting narration) that is Mursal narrated by Ash-Shafi'ee.