Bechoros Chapter 8, Mishnah 7. The fundamental principle of this Mishnah is that when the Torah mandates a specific payment - such as five shekels for the redemption of the firstborn - it refers to five specific weights of pure silver. Some technical details in this matter can be confusing, so we will begin by clarifying the simple foundations.
Two Types of Coins:
In the time of the Mishnah, coins, including the sela, were defined by their weight, and two types of selaim were used:
Tyrian silver - the coin of the city of Tyre, located on the coast of modern-day Lebanon (ancient Phoenicia), where coins were minted from pure silver.
Provincial silver - the local coin, which was made of one part silver to eight parts copper, so that the same 19-gram coin contained only one-eighth silver.
Our Mishnah comes to establish that the coins to be used are specifically the Tyrian coin - pure silver coins without the addition of copper. This is its central point.
The Shekel of the Torah and the Sela of the Mishnah:
The shekel in the Chumash is actually the sela of the Mishnah. The confusion grows because in the language of the Mishnah there is a coin called a 'shekel', and it is half a sela. Therefore, wherever the Chumash uses the phrase "five shekels in the holy shekel", the Mishnah refers to it as five selaim - and establishes that these selaim are Tyrian, made of pure silver, and not the local provincial silver which contains only one-eighth silver.
Calculating the Weights:
In ancient times - during the time of Moshe Rabbeinu, as well as in later generations, as the Rambam stated - barley grains, which have a relatively constant weight, served as a base unit. The weight of the holy shekel in the time of Moshe Rabbeinu was 320 barley grains. Back in the days of Yechezkel, the Sages added a fifth to the weight, meaning an addition of about 20% in the amount of silver, and they had the authority to do so. It turns out that the sela of pure silver stands at 384 barley grains.
Therefore, the five selaim of the Mishnah, which are the five shekels of the holy shekel in the Chumash, amount to five times 384 barley grains - 1,920 grains. According to the poskim, the Chazon Ish and Rav Chaim Naeh, the practical measure is 96 grams of pure silver. Although this measure is slightly higher than what would appear according to the calculation, this is nevertheless the halachah: 1,920 barley grains equal 96 grams, and this is the amount that must be paid. As of the time of the recording, late 2025, this is a little over 500 New Israeli Shekels, roughly equivalent to slightly more than 150 US dollars.
It is worth noting as an aside: there is a technical term called a 'grain', which is a unit of weight, just as a pound, ounce, and gram are terms of weight. That 'grain', which is generally based on a barley grain, equals 65 milligrams. However, the halachah of the Sages, including our Mishnah, proceeds from the assumption that a barley grain weighs 50 milligrams, meaning twenty grains in one gram.
The Language of the Mishnah:
"Chamesh sela'im shel ben bemaneh Tzuri" - The five sela'im given for the redemption of the firstborn son must be given in Tyrian maneh, in the currency of the city of Tyre, meaning in sela'im of completely pure silver. Similarly, in the other places in the Torah where a specific amount of money is established for payment, it refers to pure silver coins.
"Sheloshim shel eved" - A forewarned ox, an animal that has been established as dangerous, which killed a fellow Jew's Canaanite slave. On the one hand, a human life has infinite value, but on the other hand, the neighbor has lost a tangible economic asset. Therefore, the Torah established a fixed amount, so that we do not attempt to assess the value of a person, who cannot be evaluated: the penalty to the owner who lost his slave is thirty shekels, six times the amount of the redemption of the firstborn son.
"Vachamishim shel ones veshel mefateh" - The ones is the rapist, and the mefateh is the seducer. One who sleeps with a young woman outside of marriage pays her father a fixed sum of fifty shekels, ten times the amount of the redemption of the firstborn son.
"Ume'ah shel motzi shem ra" - The slanderer: one who performed the first stage of marriage, kiddushin, with a young woman, and before the second part, nisu'in and her entering his home, was completed, he plotted and brought false witnesses claiming she had committed adultery in the interim, and was found to be a liar. Aside from the lashes and similar punishments, he pays a penalty of one hundred shekels, twenty times the amount of the redemption of the firstborn son.
"Kulam beshekel hakodesh bemaneh Tzuri" - They are all based on the holy shekel of the Torah, which is the sela of the Mishnah, and their payment is in Tyrian maneh, the purest silver coin minted in Tyre.
"Vechulam nifdin bechesef uveshaveh kesef":
The main factor in all of these is the value. If the value of five sela'im of pure silver stands today at 508 Israeli shekels, this amount must be given - either in money or in any other commodity. Instead of silver coins, one can give gold coins, copper coins, palladium, bullion, or anything of value equal to that amount, and this is what is called shaveh kesef, the equivalent of money.
"Chutz min hashekalim":
Here the Mishnah establishes an exception, and the word 'shekalim' is particularly confusing: it refers to what is colloquially called the half-shekel. The Torah commands that every year, in the month of Adar, every Jewish male from the age of twenty and up must give a half-shekel for the upkeep of the Temple and the purchase of public offerings, as we learned in Tractate Shekalim. For this payment, one cannot give the equivalent of money - not gold, not palladium, not books, nor any other object that is worth money - rather, there is an obligation to give specifically a half-shekel coin.
There is one other place in halachah where specifically a coin is required and not the equivalent of money, even though the Mishnah did not mention it: maaser sheni. One who redeems his maaser sheni produce must redeem it specifically onto a coin, and bring the coins up to Jerusalem in order to purchase food items and other consumer goods there.
In summary: In this Mishnah we learned that all the fixed payments in the Torah - five sela'im for the redemption of the firstborn son, thirty for a slave killed by a forewarned ox, fifty for a rapist and seducer, and one hundred for a slanderer - are measured in the holy shekel and paid in Tyrian maneh, meaning in pure silver and not in provincial money. We explored the relationship between the shekel in the Torah and the sela in the Mishnah, the calculation of the weight in barley kernels and the addition made by the Sages, and the rule that they are all redeemed with money and with the equivalent of money - except for the half-shekel, as well as the redemption of maaser sheni, for which specifically a coin is required.