Bishr bin Asim narrates from his father, and he from his grandfather, who said: Umar (may Allah be pleased with him) appointed me over the zakah of my people, and I counted their young as well. They complained about me and said: If you count them among the sheep, then collect zakah from them too. He said: We counted them. Then I met Umar (may Allah be pleased with him) and said: My people have found fault with me because I count even the little young of their sheep, and they said: If you count them among the sheep, then collect the zakah from them too. Umar (may Allah be pleased with him) said: O Sufyan! Count among your people even those young that the shepherd carries in his hand, and tell your people: We leave for you the fine milking ewe, the pregnant one, the one kept for meat and the stud of the flock, and we take the jadha' and the thani; this is a middle course for us and for you in wealth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7314