משנה על אהלות 13:1

Sometimes they stated a smaller measure: Liquid and dry measures were measured with the Italian standard which was the one that was used in the wilderness. Sometimes they stated a measure that varied according to the individual concerned: One who takes the handful of a minhah, One who takes both hands full of incense, One who drinks a cheek full on Yom Kippur, And the two meals for an eruv, The quantity being the food one eats on weekdays and not on Shabbat, the words of Rabbi Meir. Rabbi Judah says: as on Shabbat and not as on weekdays. And both intended to give the more lenient ruling. Rabbi Shimon says: two thirds of a loaf, when three [loaves] are made of a kav. Rabbi Yohanan ben Beroka says: not less than a loaf that is purchased for a pundium when the price of wheat is four se'ah for a sela’.