In the discussion of the varying size of the “ama” (=cubit) measurement, the Gemara points to the dimensions of the Mizbei’ah – the altar in the Temple – as an example of a structure with “amot” of varying sizes.
The height of the Mizbei’ah (including the corner Keranot, or horns) was ten amot – but not all of the amot were measured the same way, so the total height was 58 tefahim (=handbreadths), rather than 60 tefahim. There were five places on the Mizbei’ah that were measured in amot of five tefahim each. They were:
The height of the Yesod (foundation)
The width of the Yesod
The width of the Sovev (the ledge around the Mizbei’ah)
The height of the Keranot (the raised corners)
The width of the Keranot
From the passage that is quoted from the book of Yehezkel (43:13) that describes the Mizbei’ah it is clear that the Navi describes the Mizbei’ah as having two different types of “ama” measurements. Nevertheless, the passages in Sefer Yehezkel that deal with the measurements of the third Temple that is to be built in the future are unclear, and they are interpreted by the Sages of the Gemara in different ways.
Following the discussion of different measurements, the Gemara brings Rabbi Hiyya bar Ashi in the name of Rav who says that the rules of Shi’urim (=measurements), Hatzitzim (=intervening substances) and Mehitzim (=partitions) are all based on an oral tradition received by Moshe on Mount Sinai.
With regard to measurements, the Gemara objects that they are, in fact, rooted in a biblical passage because Rav Hanan interprets the passage (Devarim 8:8) describing the seven species of agricultural products with which the Land of Israel is blessed, as teaching rules about measurements. Apparently Rav Hanan perceived the praise of the Land of Israel to be so significant that even a foundational law – like establishing basic measurements – could be based upon it.
As an example, Rav Hanan derives that the standard amount of food that one must eat to be held liable for eating non-Kosher (and most other prohibited foods) is the size of an olive (“Zayit”). From “Dvash” (=honey), the last of the seven species mentioned, we derive the measure of food that makes someone liable for eating on Yom Kippur – an amount of food the size of a plump date. In the realm of eating that is forbidden, Yom Kippur is unique. The Torah never forbids “eating” on Yom Kippur; rather it commands the Jewish people to suffer “inuy” – affliction – on that day. The Rabbinic Sages understood this to mean that, while we should not eat, one does not reach a level of satisfaction beyond “inuy” until he eats the amount of a date (which is larger than an olive).
The conclusion of the Gemara is that the derivations based on this passage can, at best, act as hints to the law, and that the true source is the oral tradition, as presented initially.