It is narrated from Abu Hurairah (may Allah be pleased with him) that he reports: I heard Abul Qasim ﷺ saying, "By Him in Whose hand is my soul! Whoever gives charity from lawful earnings—and Allah accepts only what is lawful—and only charity from lawful earnings reaches Allah. It is as if someone places it in the hand of the Most Merciful, then He (Allah) increases it for the giver, just as one of you raises his young animal by feeding and nurturing it, until a single morsel becomes as great as a huge mountain on the Day of Resurrection." Then the Prophet ﷺ recited this verse: "Allah is the One Who accepts repentance from His servants and accepts charities." (__QUR_N__ at-Tawbah: 104)
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 686
Hadith Takhrijاخرجه البخارى، الزكاة، باب الصدقة، من كسب طيب لقوله ويربي الصدقات ..... الخ ) (1410) ۔ ومسلم، الزكاة، باب قبول الصدقة من الكسب الطيب وتربيتها (1014)۔
It is narrated from Abu Hurairah (may Allah be pleased with him) that he said: The Messenger of Allah (ﷺ) said: "The example of the one who gives charity and the miser is like two persons wearing two coats of mail or armors from their chests up to their collarbones. When the generous person intends to spend, the armor covers his body or extends over him until it covers his clothes, and its traces disappear as he walks. But when the miser intends to spend, the coat tightens, and every ring clings to its place, until it even squeezes his neck or throat. The miser tries to loosen it, but he cannot loosen it."
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 687
Hadith Takhrijاخرجه البخارى الزكاة، باب مثل البخيل والمتصدق (1443) ۔ ومسلم، الزكاة ، باب مثل المنفق والبخيل (1021)۔
Through another chain, it is narrated from Abu Hurairah (may Allah be pleased with him) in a similar manner, but in it the words are: "that he tries to widen it, but is not able to do so."
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 688
Hadith Takhrijاخرجه البخارى الزكاة، باب مثل البخيل والمتصدق (1443) ۔ ومسلم، الزكاة ، باب مثل المنفق والبخيل (1021)۔