Wahb bin Munabbih (may Allah have mercy on him) narrates from his brother that he said: I heard Sayyiduna Mu'awiyah (may Allah be pleased with him) say that the Messenger of Allah (peace and blessings be upon him) said: "Do not be persistent in asking. By Allah, none of you asks me for anything and I give it to him from what I have while I dislike it, and then it is blessed for him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7872