en_tn_lite_do_not_use/2sa/15/21.md

As Yahweh lives, and as my master the king lives

Here the speaker is making a solemn promise. He compare the certainty the he will fulfill his promise to the certainty that Yahweh and the king are alive. Alternate translation: "I solemnly promise that as surely as Yahweh and the king live" (See: rc://en/ta/man/translate/figs-simile)

your servant

Ittai refers to himself this way to honor the king.

whether that means living or dying

"even if I get killed supporting you"