This can be stated in active form. Alternate translation: "may you do what you promised to me and my family, and may your promise never change" (See: [[rc://en/ta/man/jit/figs-activepassive]])
David is speaking about himself in the third person. This can be stated in the first person. Alternate translation: "me and my family" (See: [[rc://en/ta/man/jit/figs-123person]])