Albert Barnes Commentary Zechariah 14:21

"Yea, every pot in Jerusalem and in Judah shall be holy unto Jehovah of hosts; and all they that sacrifice shall come and take of them, and boil therein: and in that day there shall be no more a Canaanite in the house of Jehovah of hosts." — Zechariah 14:21 (ASV)

And every pot in Jerusalem and in Judah shall be holiness to the Lord – Everything is to be advanced in holiness. All the common utensils everywhere among the people of God shall not only be holy, but holiness, and capable of the same use as the vessels of the temple.

And there shall no longer be the Canaanite in the house of the Lord of hosts – The actual Canaanite had long since ceased to be; the Gibeonites, the last remnant of them, had been absorbed among the people of God. But all Israel were not of Israel. Isaiah had called its princes and people, rulers of Sodom, people of Gomorrah (Isaiah 1:10). Ezekiel had said, Thus says the Lord God to Jerusalem: Your birth and your nativity are of the land of Canaan; your father was an Amorite, and your mother a Hittite (Ezekiel 16:3). Hosea used at least the term of twofold meaning, Canaan, in whose hands are the balances of deceit (Hosea 12:7); and Zephaniah, All the people of Canaan are destroyed (Zephaniah 1:11). After the time of the Canon, Daniel is introduced saying, O you seed of Canaan and not of Judah.

Ezekiel had spoken of ungodly priests, not only as uncircumcised in heart (according to the language of Deuteronomy 10:16; Deuteronomy 30:6), but uncircumcised in flesh also, altogether alien from the people of God (Ezekiel 44:7). The prophet then speaks, as Isaiah, It shall be called the way of holiness; the unclean shall not pass over it (Isaiah 35:8), and Joel, then shall Jerusalem be holy, and there shall no strangers pass through her any more (Joel 3:17). This shall have its full fulfillment in the time of the end. There shall in no wise enter into it anything that defileth, neither whatsoever worketh abomination or a lie; and, without are dogs and sorcerers and whoremongers and murderers and idolaters, and whatsoever loveth and maketh a lie (Revelation 21:27; Revelation 22:15).

Cyril: “Although born of the blood of Israel, those of old eagerly imitated the alien Canaanites. But after the Only-Begotten Word of God came among us, and, having justified by faith, and sealed with the Holy Spirit, those who came to His grace, our mind has been steadfast, unshaken, fixed in piety. Nor will anyone persuade those who are sanctified to honor any other god save Him who is, by nature and in truth, God, whom we have known in Christ. For in Himself He has shown us the Father, saying, He that hath seen Me hath seen the Father (John 14:9).”

Therefore, he says, in that day—that is, at that time—there shall be no Canaanite—that is, alien and idolater—in the house of the Lord Almighty? Theodoret: “But may the Almighty God make the saying come true at this time also, that no Canaanite should be seen among us, but that all should live according to the Gospel laws, and await that blessed hope and the appearance of our great God and Saviour Jesus Christ; with whom be glory to the Father with the Holy Spirit, now and ever, and to endless ages. Amen.”