A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 124:1The writer, for the Church, praises God for past, and expresses trust for future, deliverance from foes. (Psa 124:1-8)
on our side--for us (Psa 56:9).
now--or, "oh! let Israel"
psa 124:2rose . . . against, &c.-- (Psa 3:1; Psa 56:11).
psa 124:3Then--that is, the time of our danger.
quick--literally, "living" (Num 16:32-33), description of ferocity.
psa 124:4(Compare Psa 18:4, Psa 18:16).
psa 124:5The epithet proud added to waters denotes insolent enemies.
psa 124:6The figure is changed to that of a rapacious wild beast (Psa 3:7), and then of a fowler (Psa 91:3), and complete escape is denoted by breaking the net.
psa 124:8(Compare Psa 121:2).
name--in the usual sense (Psa 5:11; Psa 20:1). He thus places over against the great danger the omnipotent God, and drowns, as it were in an anthem, the wickedness of the whole world and of hell, just as a great fire consumes a little drop of water [LUTHER].