# they will all grow old

The word "they" refers to "the earth" and "the heavens."

# your years will have no end

Here David describes the length of time that God is alive as his "years." This can be written in positive form. AT: "you will live forever" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-doublenegatives]])