The writer speaks of revenge on his enemies as if it were paying to them what he owes. AT: "so that I may take revenge on them" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The word "this" refers to what the writer will say next. For clarity, the clauses may be reversed. AT: "Because my enemy does not triumph over me, I know that you delight in me" (See: [[rc://en/ta/man/translate/figs-events]])
This can also be translated in future tense, since Yahweh has not yet healed him. AT: "If you enable me to do that, with the result that my enemies do not defeat me, I will know that you are pleased with me" (See: [[rc://en/ta/man/translate/figs-explicit]])
The writer speaks of being in Yahweh's presence as being in a place where Yahweh can see him and he can see Yahweh's face. AT: "will keep me with you" (See: [[rc://en/ta/man/translate/figs-metaphor]])