The abstract noun "life" can be stated as a verb. Alternate translation: "He asked that you cause him to live for a long time; you caused it to happen" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])
The idiom "the length of his days" refers to the duration of his life. Alternate translation: "a long life that lasts forever" (See: rc://en/ta/man/translate/figs-idiom)