Deeper Commentary

Psa 87:1

A Psalm by the sons of Korah; a Song-
"By" can as well be "for", so the Psalm may still be Davidic, but is dedicated to the memory of the sons of Korah. Korah had died in rebellion against God, but his children had been preserved (Num. 26:9-11); they therefore became representative of all who had overcome bad background to worship Yahweh independently, regardless of the sins of their fathers. They were therefore inspirational to the righteous remnant amongst the exiles in Babylon. Or these "sons of Korah" may refer to a group of musicians who were to perform the Psalm, the Levitical singers mentioned in 1 Chron. 26:1,2; 2 Chron. 20:19. Or if we insist on reading "by", it could have been a Davidic Psalm edited and as it were released by a group called "the sons of Korah" during the captivity in Babylon.

The title of Ps. 88 may well apply to this Psalm, according to the theory of J.W. Thirtle that some Psalm titles got attached to the Psalm ahead of them. The Hebrew words for dancing with all the might when David brought the ark to Zion (2 Sam. 6:14)  are similar to the title of Ps. 88, mahaloth leannoth, which seems to actually apply to Ps. 87, which would then reflect David's feelings at this time.  

His foundation is in the holy mountains-
Perhaps an intensive plural for the one great mountain, Zion, which he now speaks of in :2. He believes that God has founded Zion, and ultimately she will not be moved. Given the tragic history of the Jerusalem temple and the city itself, this takes some faith to believe.

Psa 87:2

Yahweh loves the gates of Zion more than all the dwellings of Jacob-
As discussed on Ps. 78, we wonder whether Yahweh had indeed loved Zion as much as David did. He appears to transfer his own excessive fondness for Zion onto God. For God made it clear to David that He doesn't live in specific geographical locations and sacred spaces, but in the hearts of men. And in ps. 78 David argued, perhaps too far, that God had rejected Ephraim and Shiloh, and chosen Judah, David and Zion. See on Ps. 78:51,68,69,72.

Psa 87:3

Glorious things are spoken about you, city of God. Selah-
What exactly had God spoken specifically about Zion, given His statements that He doesn't live in specific geographical locations and sacred spaces, but in the hearts of men? See on :2. It could be that this verse is simply a preface for the revelations about Zion which David now makes. But we wonder whether this is actual revelation from God, or just the inspired record of what David wished to be true of Zion. The word for "glorious things", things of "honour", is used of how God honours persons and behaviour rather than geographical locations and spaces. 

Psa 87:4

I will record Rahab and Babylon among those who acknowledge me. Behold, Philistia, Tyre and also Ethiopia: This one was born there-
The vision is of the Gentiles from all points of the compass [that appears to be the reason behind the choice of the nations here listed] accepting Zion and being born within her. The Gentiles were to come and dwell in Zion, and this would be a cause of joy to the spiritually minded Israelite (see on :7). This "birth" in Zion may be another way of saying that they were equally Israelite as the ethnic Jews who were born there. God's Israel would be predicated upon spiritual and not ethnic lines.

Psa 87:5

Yes, of Zion it will be said, This one and that one was born in her; the Most High Himself will establish her-
As explained on :4, the birth of Gentiles in Zion is to be understood as their conversion to the God of Israel there in Zion, presumably through visiting the temple which David envisaged being built there and being taught there. The promise to David was that his kingdom and his throne, reigned upon by his great Messianic seed, would be "established" by God eternally (1 Chron. 17:11,12,14 s.w.). But he appears to have become over literal and religious in interpreting this as meaning that Zion itself would be eternally established. The account of bringing the ark to Zion is prefaced by the record of David's sons who were born in Jerusalem. But we read nothing further about them. This could all be read as part of David's attempt to establish his own dynasty in Zion, which God responded to in 2 Sam. 7 by saying that He would establish David's Kingdom in His own way, through David's seed, the Lord Jesus. Likewise in Ps. 132:17  David puts words in God's mouth: "There [in Zion / Jerusalem] will I make the horn of David to bud". But the budding of David's horn was fulfilled by God in the resurrection of the Lord Jesus, the great "son of David", rather than in David having many sons in Jerusalem.

Psa 87:6

Yahweh will count, when He writes up the peoples, This one was born there. Selah-
The idea may be that at the final count at judgment day, God would accept as His true people those Gentiles who had been "born" in Zion, who had there made a commitment to His covenant (see on :4,5). But David may be hinting that his dynasty was going to reign eternally from Zion and his long line of kings which he envisaged would all be born there. God interjected His promises of 2 Sam. 7 onto David's plans. David's line was indeed long but it was broken, the temple was destroyed, and Zion was ploughed over. The eternal dynasty only came true through the Lord Jesus and God's grace, not through David's efforts to self establish.

But this had specific potential reference to the restoration. Ezra 2:62 records Judah being ‘reckoned by genealogies’, using the same Hebrew word which is the hallmark of 1 Chron. (4:33; 5:1,7,17; 7:5,7,9,40; 9:1,22). And in this context, Is. 40:26 compares God’s ‘bringing out’ of Judah from Babylon with His ‘bringing out’ the stars by their individual names, all wonderfully known to Him. Ps. 87:6 had prophesied something similar about the restoration of Zion’s fortunes: “The LORD shall count, when he writeth up the people, that this man was born there”. The Kingdom of God was to be the restoration of Israel’s Kingdom- but they had to actually get on and restore it rather than wait for it to come. This is another reason for understanding Ezekiel’s temple as being broadly of the same dimensions as that of Solomon. 

Psa 87:7

Those who sing as well as those who dance say, All my springs are in You-
LXX "The dwelling of all within thee is as the dwelling of those that rejoice". Those dwelling within Zion are the Gentiles who have accepted Zion and the God of Israel who is manifest there (:4); and far from being nationalistic and elitist,  the Jews were to rejoice in this conversion of the Gentiles.