Ibn Umar used to give the zakat of Ramadan using the first mudd of the Prophet ﷺ, and likewise for the expiation of an oath he used the mudd of the Prophet ﷺ.Abu Qutayba said, Malik said to us, "Our mudd is larger than your mudd, and we see no merit except in the mudd of the Prophet ﷺ."Malik also said to me, "If a ruler came to you and struck a mudd modeled on the mudd of the Prophet ﷺ, by what measure would you then give?"I replied, "We would give by the mudd of the Prophet ﷺ."He said, "Do you not see, then, that the matter ultimately returns to the mudd of the Prophet ﷺ?"
كان ابن عمر يعطي زكاة رمضان بمد النبي ﷺ المد الأول، وفي كفارة اليمين بمد النبي ﷺ قال أبو قتيبة: قال لنا مالك: مدنا أعظم من مدكم، ولا نرى الفضل إلا في مد النبي ﷺ. وقال لي مالك: لو جاءكم أمير فضرب مدا من مد النبي ﷺ بأي شيء كنتم تعطون؟ قلت: كنا نعطي بمد النبي ﷺ قال: أفلا ترى أن الأمر إنما يعود إلى مد النبي ﷺ؟
Bukhari narrated it in the Book of Expiations for Oaths (6713), from Mundhir bin Walid Jarudi, who said, Abu Qutayba (who is Muslim) narrated to us, saying, Malik narrated to us, from Nafi, and he related it as mentioned.His statement, "the first mudd," refers to the mudd of the Prophet ﷺ, which was a fixed measure associated with him. Nafi meant by this that he would not give using the mudd that Hisham had introduced.As for Malik's statement, "our mudd is greater than your mudd," he meant this in terms of blessing, that is, the mudd of Madinah. Even though it was smaller in quantity than Hisham's mudd, the mudd of Madinah was distinguished by the blessing resulting from the Prophet's supplication ﷺ for it, and so it was greater than Hisham's mudd. This was stated by Hafiz in Fath al-Bari (11/598).