Abu Sa'id al-Khudri reported Allah's Messenger (way peace be upon him) as saying:
No sadaqa (zakat) is payable on less than five wasqs of (dates or grains), on less than five camel-heads and on less than five uqiyas (of silver). (DE)
Reference (DE): Sahih Muslim 979 a (DE)
In-book reference (DE): Book 12, Hadith 1 (DE)
USC-MSA web (English) reference(deprecated numbering scheme): Book 5, Hadith 2134 (DE)