Sunan At-Tirmidhi

Abu Hurairah narrated that :the Messenger of Allah said: ""None gives charity from Tayyib - and Allah does not accept but Tayyib - but that Ar-Rahman accepts it with His Right (Hand). Even if it is a date, it is nurtured in the Hand of Ar-Rahman until it is greater than a mountain, just as one of you nurtures his foal or young camel