The two lines of verse 1 are parallel: rejoices (as in 9.2) and exults (as in 9.14). In thy strength is synonymous with in thy help (that is, “victory”; see comment on 3.8), both referring to the fact that Yahweh has given the king the power to defeat his enemies in battle. It was by means of the strength and the help that Yahweh gave him that the king was able to defeat the enemy. The king rejoices must often be expressed idiomatically; for example, “the chief’s heart is white” or “the chief’s heart rests coolly.” Here thy help means “the victory you gave him”; this translates the same Hebrew word (“salvation”) which is translated “deliverance” in 3.8. Good News Translation “answered his request,” care should be taken to avoid a rendering which means “gave a verbal rely to what he asked.” Here the meaning may be translated, for example, “you, God, have given him the things he asked you for” or “you have let him have everything he asked for.” Translators should avoid the use of a positive statement in a and a negative in b, if that form is not stylistically acceptable.

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 .