How the Shekels of Ephron Were Weighed as Heavy Kantarin

Yalkut Shimoni on Torah 102:20

Rabbi Hanina said: The shekels mentioned in the Torah are sela coins; in the Prophets they are litrin [a larger weight]; in the Writings they are kantarin [a still heavier weight] — except for the shekels of Ephron, which are kantarin, as it is said, "four hundred shekels of silver, current money with the merchant" (Genesis 23:16). It goes out as merchandise [the phrase "current with the merchant" shows the coin was reckoned at the heaviest commercial standard].

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