Rashi

I say to the Lord, “You are my God.” do not take me away in the middle of my days Do not take us away to destroy us from the earth in the hands of our enemies in the middle of our days. And what are our days? All the days of all generations, of Your years, You promised to keep us alive before You, as he says at the end of the psalm, “and Your years do not end...and their seed will be established before You.”