One of the actions prohibited on the Sabbath is taking items from the private domain and carrying them into the public domain. These items, the sages ruled, have a minimum size which makes one who carries them from domain to domain liable for violating the Sabbath rest and will make him subject to punishment. One who takes an item of a size people do not use from one domain to another is not punished; for example, one who moves from domain to domain a piece of paper too small upon which to write two large letters is not punished. Thus for one who takes olive oil from domain to domain; the early sages ruled that the minimum amount of oil is enough to rub in a small limb. One who moves less than that from domain to domain is not punished. The scholars gave more details about the measure of oil and ruled that it is the amount needed to rub into the small limb — a pinky joint — of a day-old infant. The scholars asked the scholars above: In a different place the early sages ruled that the minimum measure of oil is “enough to rub into a small limb, and a day-old infant.” Given the conjunction, and a day-old infant,” the implication is that the small limb is of an adult. Answer; The interpretation of the words of the early sages should be “oil enough to rub into the small limb of a day-old infant.” The scholars argued that the disagreement over the minimum measure of olive oil is based on a disagreement between the early sages — one sage, R’ Simeon son of Elazar, ruled that the minimum measure of oil is “enough to rub into a small limb, and a day-old infant.” Another sage, Rabbi Nathan, ruled that the minimum measure of oil is “enough to rub into a small limb.” This means, the scholars argued, that the first sage set the amount as enough to rub into the pinky joint of a day-old infant and the second sage as enough to rub into the pinky joint of an adult. The scholars rejected this interpretation and ruled that the disagreement between the early sages is not over the measure of olive oil but whether the pinky joint of an adult is the same size as a large limb of a day-old infant. In the end the scholars ruled that the minimum measure of olive oil which makes one liable to punishment for carrying from domain to domain is enough to rub into a small limb of a day-old infant.
(Babylonian Talmud, Tractate Shabbat 87b-88a)