Abarim Publications' online Biblical Hebrew Dictionary
The verb צרף (sarap) describes the metallurgic process of smelting, refining and testing metals. It's highly significant that metallurgic technology developed along with the Biblical narrative; the iron age didn't get going in the Levant until the time of king David. There was iron prior to that but no technology to refine it and make it useful.
This metallurgic technology developed on a par with the technology involved with making fires in kilns and furnaces; the hotter a nation could make its fires (Daniel 3:19), the cleaner it could make its metals, and the stronger it could make its instruments, tools and weapons. In other words: the hotter the fire, the stronger the nation.
Because copper has the lowest melting point of the metals that are solid at room temperature, metallurgy began with the manufacturing of copper and bronze. And whoever possessed the technology to make metal from stones, was nothing short of a magician (old-world magicians weren't mostly entertainers and certainly not endowed with paranormal talents, they were mostly engineers endowed with proper knowledge of real technology). Ergo, the word for bronze, נחוש (nahush) is closely similar to נחש (nahash), meaning to divine, and it's obviously not a very big step between refining metals by applying fire and refining people by applying instructions and corrections (in the broadest sense). Hence our verb צרף (sarap) is most often deployed with just that function (Jeremiah 6:29, Isaiah 1:25, Zechariah 13:9, Daniel 11:35).
Equally significant is the way the Bible speaks about itself — not fallen ready-made from heaven, or copy-pasted from the Holy Spirit's dictation, as many believe, but rather conceived, discussed, tried, improved, edited and purified according to the Holy Spirit's ever so gentle inspirations: The words of YHWH are pure words, as silver tried in a furnace on the earth, refined seven times (Psalm 12:6); every word of God is tested (Proverbs 30:5, Psalm 18:30) and purified (Psalm 119:140).
These statements obviously also shed more light on the idea that the Lord is our Rock; he is not only a foundation to build a house on, but also the source of metals (2 Samuel 22:47, Psalm 18:31, 89:26). That is why truth may be compared to a sword (Ephesians 6:14), which in turn comes out of the Lord's mouth (Revelation 1:16).
Our verb comes with the following derivatives:
- The adjective look-alike masculine noun צרפי (sorepi), meaning goldsmiths as a collective; the metallurgic guild. This noun is used only once, in Nehemiah 3:31
- The masculine noun מצרף (marep), literally meaning place, instrument or agent of metallurgy. It's used twice but in the same saying: Proverbs 17:3 and 27:21. Translations generally interpret this word as crucible (NIV, BDB Theological Dictionary, HAW Theological Wordbook of the Old Testament) or (re)fining pot (KJV, NAS, JSP, Darby, Young).