Tosefta do Liczb 15:20

When the sages entered the vineyard at Yavneh, they said, “In the future there will be an hour when a person will search for a matter among the words of Torah and will not find it in, in the teachings of the scribes and will not find it. As it says, ‘Behold, days are coming, says the Lord. . . they will seek out the word of God and they will not find it’ (Amos 8:11-12). ‘The word of God,’ this is prophecy. ‘The word of God,’ this is [knowledge] of the eschaton. ‘The word of God,’ that one matter in the words of Torah is not similar to another.” They said, “Let us begin from Hillel and Shammai.” Shammai says, [dough made] from a qav [of flour] requires challah [to be taken]. Hillel says, from two qavs. But the Sages say, it is not according to this one or that one, rather [dough made] from a qav and a half requires challah [to be taken], as it says, “The first of your kneading” (Numbers 15:20). [Challah is taken] according to your kneading. And how much is “according to your kneading”? According to your kneading in the wilderness. And how much is “your kneading in the wilderness”? [An amount equal to] the omer [offering], as it says, “The omer is a tenth of an ephah” (Ex 16:36). The Sages measured seven fourths and a little more from that of the wilderness, which are five Tzipporit quarters and a Jerusalem qav and a half.