Volume 2 · Book 24 · Hadith 515
Narrated Asma' bint Abu Bakr: that she had gone to the Prophet and he said, "Do not shut your money bag; otherwise Allah too will with-hold His blessings from you. Spend (in Allah's Cause) as much as you can afford. "
— Sahih Bukhari, Volume 2, Book 24: Obligatory Charity Tax (Zakat), Hadith #515