[Psalm 87:7] is by any reckoning a very strange verse. The suggestion has even been made that it is not part of the poem, as such, at all, but a rubric or stage direction: ‘At this point the singers and dancers will perform All my Fountains are in You’! As if to balance that, verse 1 looks more like a title than a first line. Literally, it reads simply ‘His foundation on the holy mountains’.Michael Wilcock, The Message of Psalms 73–150: Songs for the People of God. The Bible Speaks Today (Nottingham: IVP, 2001), p.58
I’ve not found this particular suggestion about 87:7 in any of the commentaries on the Psalms I have easy access to, but I’d love to know who originally suggested it – unless, of course, this is Wilcock being modest about his own take on the verse.