Sahih Bukhari
Holding Fast to the Quran and Sunnah
Volume: 009 / Book Number: 092 / Hadith Number: 430
Narrated As-Sa'ib bin Yazid:
The Sa' (a kind of measure) during the lifetime of the Prophet used to be equal to the one Mudd (another kind of measure) and one third of a Mudd which we use today, but the Sa' of today has become large.