Sunan Ibn Majah, Chapter: The Chapters Regarding Zakat

he heard Abu Hurairah say: "The Messenger of Allah (saw) said: 'No one gives charity from good sources - for Allah does not accept anything but that which is good - but the Most Merciful takes it in His right hand, even if it is a date, and it flourishes in the Hand of the Most Merciful until it becomes bigger than a mountain and he tends it as anyone of you would tend to his colt (i.e., young pony) or his young (weaned) camel.'"