Psalms 137:8

“O daughter of Babylon - That is, Babylon itself; the city of Babylon. On the word “daughter” as thus used, see the notes at Isaiah 1:8. Who art to be destroyed - Certainly to be destroyed; of whose destruction there are fixed and absolute prophecies. See the notes at Isaiah 13:19-22. Happy shall he be that rewardeth thee as thou hast served us - Margin, that recompenseth unto thee thy deed which thou didst to us. Literally, “Happy shall he be who shall repay to thee the recompence which thou hast recompensed unto us.” The idea is, who shall repay thee for thy treatment of us; or, as we should say in common language, “Who shall pay thee back?” That is, he will be esteemed a fortunate man who…”

“Happy - As being God's instrument to vindicate his honour, and execute his just judgments. Next: Psalms Chapter 138”

“daughter: Isa 47:1-5; Jer 50:42, Jer 51:33; Zac 2:7 who art: Isa. 13:1-22, 14:4-24, Isa 21:1, Isa 47:1; Jer 25:12-14, 50:1-51:64; Rev 14:8-11, 17:1-18, Rev 18:6 destroyed: Heb. wasted happy: Psa 149:6-9; Isa 13:3-5, Isa 44:28; Rev 17:5, Rev 17:6, Rev 17:14, Rev 18:6, Rev 18:20 rewardeth: etc. Heb. recompenseth unto thee thy deed which thou didst unto us, Jer 50:15-29; Rev 18:6 Psalms 137:9”