From Sahih Muslim (Hadith 2342):
Abu Huraira reported Allah's Messenger (ﷺ) as saying:If anyone gives as Sadaqa the equivalent of a date from that (earning) earned honestly, for Allah accepts that which is lawful, the Lord would accept it with His Right Hand, and even if it is a date, it would foster in the Hand of the lord, as one of you fosters his colt, till it becomes bigger than a mountain
Reference: Muslim 2342