Hadith 5:118
Abu Bakr narrated to us, he said: Abd al-Salam narrated to us, from Khasif, from Abu Ubaydah, from Abdullah, from the Prophet (may Allah bless him and grant him peace), who said: "In thirty cows, there is a tabi' or a tabi'ah (a one-year-old calf). And in forty, there is a musinnah (a two-year-old cow)."
حدثنا أبو بكر قال حدثنا عبد السلام عن خصيف عن أبي عبيدة عن عبد الله عن النبي صلى الله عليه وسلم قال في ثلاثين من البقر تبيع أو تبيعه وفي أربعين مسنة