“For on my holy mountain.” That is, Mount Zion in Israel. When Ezekiel was prophesying, Israel and Judah had been captured by foreign armies and scattered throughout foreign lands. But just as there had been an exodus from Egypt and Israel got its own land, now Ezekiel foretells of another exodus, with the faithful people of Israel leaving their exile and being regathered in Israel and worshipping God on His holy mountain. That regathering is still future.
“on the highest mountain of Israel.” The literal Hebrew is difficult to understand: “On the mountain of the height of Israel.” The meaning is the highest mountain of Israel (cp. NAB). In the Millennial Kingdom, the mountain on which God’s Temple and the city of Jerusalem are located will be the highest mountain in the world. Other verses that say that Mount Zion will be the highest mountain include Isaiah 2:2 and Micah 4:1. [For more on the Millennial Kingdom of Christ, see Appendix 3, “Christ’s Future Kingdom on Earth”].
“all the house of Israel, all of them, will serve me in the land.” Although by Ezekiel’s time the northern kingdom of Israel, consisting of the ten northern tribes, had been long before carried away by the Assyrians (2 Kings 17:6), the prophecy was that Israel would be regathered and would serve God in the land of Israel. [For more on the ten lost tribes of Israel being regathered in the Millennial Kingdom, see commentary on Jer. 32:37].
“there…there…there.” When God reestablishes Israel, which will be in the Millennial Kingdom, the Temple will be on Mount Zion and the worship of Yahweh will happen there. There is a clear emphasis in this verse that it will be “there,” on Mount Zion in Israel, that Yahweh will be worshipped. Ezekiel’s prophecy of that fact would be very comforting and encouraging to the people listening to Ezekiel who had been carried as captive to Babylon and places some 600 miles east of Jerusalem.