This is one of the strongest oaths David could swear, as Yahweh is the witness. Alternate translation: "I swear on the life of Yahweh" (See: [[rc://en/ta/man/jit/figs-idiom]])
Here "life" refers to David himself. This means that Yahweh has kept David alive. Alternate translation: "who rescued me" (See: [[rc://en/ta/man/jit/figs-synecdoche]])