2:11, 12 Echoing the promise to Abraham (Ge 12:3), many nations will join themselves to the Lord (cf. 6:15; 8:20–23; Is 2:2–4; 56:6, 7; 60:3). But this will not alter God’s choice of His people, they will still be “His portion in the holy land” (cf. Dt 32:9).
MacArthur Study Bible
2:11 The nations too will come and join themselves to (enter covenant with) the Lord in that day (see Isa. 56:3–5; Jer. 50:3). The result will be Jews and Gentiles together in one nation, my people, with the Lord dwelling in their midst (cf. Eph. 2:13–16).
ESV Study Bible
2:11 on that day Refers to the day that Yahweh returns to Jerusalem.
they will be my people The Israelites were the original people of Yahweh, the nation He redeemed from Egypt (see Exod 3:7; 5:1; 6:7). This verse proclaims that foreigners have the same opportunity to become the people of God. See note on Jer 30:22; note on Ezek 11:20; compare Zech 8:7–8.
The covenant formula (Lev 26:12) that had reflected Israel’s special relationship with Yahweh will one day be extended to include all nations. Prophetic oracles of restoration often hinted at Yahweh’s plan for future rule of the nations where the nations would also worship Yahweh in Jerusalem (e.g., Isa 56:6–7). See Isa 2:2–4; note on Zech 2:2.
Faithlife Study Bible
2:11 many nations. The extent of the vision transcends anything the Jews could accomplish in their day. The vision captures a time when salvation will not be limited to the Jewish nation but will extend God’s grace to the world. That day has come in Christ’s inauguration of the kingdom of God.
Reformation Study Bible