Hadith 2268
It is narrated from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) sent him to Yemen (as governor) and instructed him: "Take as zakat one-year-old calf from every thirty cows, and one two-year-old cow from every forty cows, and from every adult (non-Muslim person) take one dinar or a piece of Ma'afiri cloth equal to its value." This narration is from Ishaq bin Yusuf.
Hadith 2269
It is narrated from Sayyiduna Amr bin Hazm (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) had a written document prepared for him, in which it was written: "The zakat of cows is that for every thirty cows, a one-year-old calf is due, and for every forty cows, a two-year-old calf is due as zakat."