Musannaf Ibn Abi Shayba 7:71

Ibn ‘Ulayyah narrated to us, from Sa‘id ibn Yazid ibn Maslamah, who said: I asked Jabir ibn Zayd about feeding the poor person in the expiation for an oath. He said: "A meal." I said: "Al-Hasan says a *makkuk*." I then said: "What is your opinion on a *makkuk*?" He said: "A *makkuk* of wheat does not suffice."