Musnad Imam Shafi'i

Bashar bin Asim narrates from his father that Umar (may Allah be pleased with him) appointed Abu Sufyan bin Abdullah as the collector (of zakat) in Ta’if and its surrounding areas. When he went out to collect charity (zakat), he counted the young animals (offspring) along with the adults. While they did not take zakat from those young ones, the people said: “If you are counting these young ones, then you should also take them from us as zakat.” He refrained (from collecting zakat) until he came to Umar (may Allah be pleased with him) and said to him: “Be aware that these people think that you are counting their young animals but by not taking zakat from them, you are being unjust to them.” So Umar (may Allah be pleased with him) said to him: “Count their young animals as well, even the one (so small) that the shepherd carries in his hand, and say to them: I will not take from you a suckling animal, nor one close to giving birth, nor a milking animal, nor a fattened animal for slaughter, nor a billy goat used for mating with the goats. And take from them an ‘anaq, a jadh’ah, and a two-year-old animal, and this is of average quality between the bad and the good.”