Sayyiduna Malik bin Nadlah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Hands are three: the Hand of Allah is the uppermost, the hand of the giver is the one next to it, and the hand of the one who asks is the lowest. So give away what is surplus, and do not make yourself helpless."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7885