Here "Jacob" refers to the descendants of Jacob. Alternate translation: "Yahweh will have mercy on the descendants of Jacob" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The house of Jacob refers to the descendants of Jacob, the Israelites. Alternate translation: "unite with the descendants of Jacob" (See: [[rc://en/ta/man/translate/figs-metonymy]])