The sixth chapter of Deuteronomy opens with these words:
Now these are the commandments, the statutes, and the judgments, which the LORD your God commanded to teach you, that ye might do them in the land whither ye go to possess it: That thou mightest fear the LORD thy God, to keep all his statutes and his commandments, which I command thee, thou, and thy son, and thy son's son, all the days of thy life; and that thy days may be prolonged. (Deuteronomy 6:1-2)
Keyed to the word prolonged is the following note from page 235 of The Dake Annotated Reference Bible:
The word prolong with its various endings is used 25 times, nearly always of life on earth being extended if certain conditions are met.