The phrase by thee means “with your help” or “you enable”; so Good News Translation “You give me strength.” The verb in line a is translated crush by Revised Standard Version; it seems more likely that it means “run to,” that is, “attack” (Good News Translation, Biblia Dios Habla Hoy). See New International Version “advance against”; Bible en français courant “launch an assault.” Hebrew Old Testament Text Project says the Hebrew verb may be translated in various ways: “I will run (against) a band (of raiders)”; “I will dislodge a band (of raiders)”; “I will crush a band (of raiders).”

A troop means a band or group of warriors; however, the parallel in the next line (“a wall”) and one Greek translation of the parallel in 2 Samuel 22.30 lead some scholars to conjecture here in line a a word meaning a wall of stones instead of a troop. So New English Bible, New Jerusalem Bible, Bible en français courant; New Jerusalem Bible “rush a barrier”; Bible de Jérusalem “break through the ramparts.” A troop or a “band of warriors” may be rendered as a “line of soldiers.” In some languages it will be necessary to make explicit, as does Good News Translation, how God enables the writer to perform these feats; for example, “when you make me strong,” or “because you are with me…,” or “because you help me….”

Leap over a wall in line b means to break through (literally “climb up”) a wall around a city, which defends it against enemy attacks. Therefore many English translations have “scale a wall,” which means to climb over it. In translation it may be necessary to say, for example, “a wall around a city” or “a wall which protects a city,” in order not to give the idea of the wall of a house.

Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .