His foundation is in the holy mountains.
Psalms 87:1-7.-Zion is the city loved and founded by God (Psalms 87:1-3); it is the spiritual birthplace of the nations (Psalms 87:4-7). Thrice in Psalms 87:4-6 it is stated that such and such a one "was born in her" (there); in Psalms 87:7 the chorus of converted nations joyfully sing that the springs of their spiritual life flow from her. The occasion was probably Jerusalem's triumph, under Hezekiah, over Sennacherib. "Babylon" and Egypt ("Rahab:" cf. Isaiah 30:7; Isaiah 51:9; Psalms 89:10) were in power. After Nebuchadnezzar's of Egypt at Carchemish Egypt was no longer so. This Korahite-Yahweh (H3068) psalm is akin to the Korahite-'Elohiym (H430) psalm, Psalms 46:1-11. Zion alone was granted the favour, above the other cities of Judah, that it alone escaped the Assyrian yoke (Psalms 87:2; Isaiah 37:38). The conversion of the nations was an anticipation suggested by 2 Chronicles 32:23 (cf. Psalms 76:11). The nations specified were those threatened by Assyria-Egypt, Ethiopia (which, under Tirhakah, made a diversion in favour of Jerusalem), Babylon, the rising rival of Assyria, which sent presents to Hezekiah (Isaiah 39:1-2), Philistia, and Tyre (Isaiah 14:29; Isaiah 20:1).
His foundation is in the holy mountains. "His foundation" - i:e., the city of God (Psalms 87:3), founded by HIM х yªcuwdaah (H3248), the same as yªcowd (H3247), a feminine termination being given to suit Zion] (cf. the parallel, Isaiah 14:32). Compare Isaiah 54:11; Isaiah 54:14 as to God's future 'laying of Zion's foundations with sapphires,' and 'establishing her in righteousness' (cf. Psalms 87:5 Psalms 87:5 here). Spiritually, Zion was 'founded' when it was chosen as the seat of the sanctuary, its true foundation. The plural, mountains," is used because Zion is one part of a mountain range. It gave sanctity to the whole range. The sanctity of the mountains implies their separation from other hills as sacred to God, and as being therefore inviolably secure, so long as the people, by faithfulness, had God among them (cf. Psalms 68:16).