Bede

Because a multitude of Gentiles followed it after Judah came to faith in the Lord's incarnation and an astonished partaker of the same grace hastened its own unexpected conversion, Judah exclaimed in surprise, "Who is this that ascends from the desert, flowing with delights, leaning upon my beloved?" The church of the Gentiles ascends from the desert because the one who was deserted by its Creator for a very long time now arrives at his grace by the incremental steps of faith and good works, thus fulfilling what the prophet Isaiah …

Commentary on the Song of Songs 5:8.4-5 ↗

Thomas Aquinas

Second, he promises the fertility of the land: the glory of Libanus, that is, the fertility of various things, which is the glory of these places, will be found in the promised land: his glory shall be as the olive tree: and his smell as that of Libanus (Hos 14:7). Third, the nearness of both of these: they themselves shall see, that is, it shall not be postponed to the time of their children, above: his eyes shall see the king in his beauty (Isa 33:17).

Commentary on Isaiah ↗