Furnace, treasury, potter?
Per Smith (WBC):
יוֹצר is often emended to אוֹצר "treasury" following the Syr[iac]. C. C. Torrey argued convincingly that there was a foundry in the second temple which melted the gold and silver that was given to the temple. The minor temple official responsible for the "money" was יוצר "moulder...."
After the prophet is rejected by the people he asks for the wages he earned as their shepherd, leaving the amount up to his employers. They weighed (verb שקל, "shekeled") out "thirty" (shekels = a unit of weight) of silver. Then Yahweh commanded him to cast it (his wages) to the potter (יוֹצר MT). The Syriac has treasury איצר. So the prophet took the noble price (irony) and cast it to the potter (יוֹצר) in the house of Yahweh.
The term יוֹצר "potter" in v 13 in the MT has caused some consternation for many interpreters. Why would the prophet cast his wages to the potter? Was there a potter working in the temple? Can the word יוֹצר refer to a shaper of metals as well as to a shaper of clay? Was the word in the original text אוֹצר "treasury" (cf. Neh 10:39; Jer 38:11), as the Syriac has it, rather than יוֹצר "potter"? The overwhelming weight of the evidence favors יוֹצר "potter" as the original reading. But according to Torrey it can mean "one who melts and moulds metal."1
This passage is quoted in Matthew 27:9–10, and St. Matthew picked up on the translation ambiguity in this passage:
Matthew cited this verse as a prophecy fulfilled by Judas Iscariot in his betrayal of the Lord for thirty pieces of silver, the prescribed price of a slave (Ex. 21:32).
There is a curious confusion of words in this text of Zechariah, however, perceived by Matthew as pointing to a deeper layer of meaning. In the traditional Hebrew reading, the Lord tells the prophet, "Cast it to the potter (el-hayoser)." Zechariah goes on to say, "So I cast it, in the house of the Lord, to the potter," a reading reflected in several modern translations.
With the change of only one letter, however, the Hebrew text would read, "Cast it into the treasury (el-hahoser)," and "So I cast it, in the house of the Lord, into the treasury." This latter reading is followed by other translations.
Rather than choose between these two possible readings, however, the Gospel of Matthew conflates them, maintaining both the temple treasury and the potter. Thus, Judas Iscariot, realizing the gravity of his betrayal but despairing of God's mercy, returns to the temple and throws in the thirty shekels....
The temple officials collect the coins. Their first thought is to put them into the temple treasury (hahoser), but they are afflicted by a hypocritical scruple about such a use of blood money. Instead, they take the coins and purchase the "field of the potter (hayoser)." The double disposition of these coins of Judas was a fulfillment of a prophetic word spoken centuries earlier in that mystic text of Zechariah.2