St. Augustine and Cassiodorus: Commentary on Psalm 7:8

et synagoga populorum circumdabit te et propter hanc in altum regredere

The Latin of this verse is somewhat obscure but the ancient commentaries are a big help.

St. Augustine:

6. [V. 8] And a congregation of people shall surround thee. This may be taken in two ways. The congregation of people may be understood either of believers or of persecutors, since our Lord's humility had this twofold result. The crowd of persecutors surrounded Him because they despised His humility; of these we read: Why have the Gentiles raged, and the people devised vain things? But the crowd of those who believed in Him in virtue of His humility also flocked around Him, so much so that it was true to say: Blindness in part hath happened to Israel, until the fulness of the Gentiles should come in: and again: Ask of me, and I will give thee the Gentiles for thy inheritance, and the utmost parts of the earth for thy possession.

And for their sakes return thou on high. For the sake of this multitude of people, return thou on high. This, as we know, Christ did, by rising from the dead and ascending into heaven. Thus glorified, He sent the Holy Spirit; for before Christ was raised to glory the Spirit could not be given. The Gospel tells us so. For as yet the Spirit was not given, because Jesus was not yet glorified. Thereupon, having returned to heaven for the sake of the multitude of the people, He sent the Holy Spirit, with whom the preachers of the Gospel were filled when in their turn they filled the whole world with churches.

Cassiodorus:

8. And a synagogue of people shall surround thee, and for their sakes return thou on high. The psalmist earlier begged Him to come, but now he reveals what can result at His coming. It is as if he were saying: "You indeed will come to deliver, but the Jewish people will persecute you with lunatic hearts." Synagogue here denotes a gathering of wicked men, not a group of religious minds, for if the whole Jewish people had believed in Him, they would have received Him before all with devoted hearts. And for their sakes return thou on high: their here refers to the people of the synagogue, who with rigid habits remained unpledged, and He could not dwell in it since He withdrew himself from its infidelity. Return thou on high is here because the gospel says: No man hath ascended into heaven but he that descended from heaven. Returning means retracing the same path to the place from where you came. In another psalm he is to say of this glorious ascension: And he ascended upon the Cherubim, and he flew upon the wings of the winds, and he made darkness his covert.