Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) says: the Messenger of Allah (peace and blessings be upon him) would give me (something), and I would say: "Give it to someone who is more in need than me." So the Messenger of Allah (peace and blessings be upon him) said: "Take it. Whatever of this wealth comes to you without your craving it and without your asking for it, take it; and whatever is not like that, do not chase after it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7887