Narrated Abu Said Al-Khudri: Some Ansari persons asked for (something) from Allah's Apostle (p.b.u.h) and he gave them. They again asked him for (something) and he again gave them. And then they asked him and he gave them again till all that was with him finished. And then he said "If I had anything. I would not keep it away from you. (Remember) Whoever abstains from asking others, Allah will make him contented, and whoever tries to make himself self-sufficient, Allah will make him self-sufficient. And whoever remains patient, Allah will make him patient. Nobody can be given a blessing better and greater than patience."
Translation of Sahih Bukhari, Book 24: Obligatory Charity Tax (Zakat), Volume 2, Book 24, Number 548