Musannaf Ibn Abi Shayba 35:215

Abdullah ibn Numayr narrated to us, from Ibn Abi Layla, from al-Hakam, who said: The Prophet, may Allah bless him and grant him peace, sent Mu'adh and ordered him to take from every thirty [cows] a *tabi'* (a one-year-old calf) or a *tabi'ah* (a one-year-old female calf), and from every forty [cows] a *musinnah* (a two-year-old cow). They asked him about the surplus between them, so he refused to take anything until he asked the Prophet, may Allah bless him and grant him peace. He said: "Do not take anything."