The word "this" refers to what the writer will say next. For clarity, the clauses may be reversed. Alternate translation: "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. Alternate translation: "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]])