Abu Dawud
Zakat
Book Number: 003 / Hadith Number: 1601
Narated By Sahl ibn AbuHathmah : AbdurRahman ibn Mas'ud said: Sahl ibn AbuHathmah came to our gathering. He said: The Apostle of Allah (pbuh) commanding us said: When you estimate take them leaving a third, and if you do not leave or find a third, leave a quarter.