People would raise their hand when they made a promise or pledge, so raising the hand represents making a promise. Alternate translation: "a promise was made" (See: [[rc://en/ta/man/jit/figs-metonymy]])
This can be stated in active form. Alternate translation: "Yahweh lifted up his hand" or "Yahweh made a solemn promise" (See: [[rc://en/ta/man/jit/figs-activepassive]])