Musannaf Ibn Abi Shayba 18:35

Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Sa’id, from Qatadah, from Sa’id ibn al-Musayyib and Abd Rabbih, from Abu Iyad, that Uthman and Zayd ibn Thabit said regarding the *mughallatah* (the case of a fatal error or severe mistake in judgment/ruling): Forty *jadha’ah* (four-year-old camels) that are *khalfah* (pregnant), thirty *hiqqah* (three-year-old camels), and thirty *bint labun* (two-year-old female camels).