In the Bible, Jesus himself never promises that a person's life lasts threescore and ten, or 70 years. However, Psalm 90:10 does make a reference to that period of time, saying, "The days of our years are threescore years and ten."
Since a "score" means 20, "threescore and ten" refers to the number 70. "Threescore equals three times 20, or 60. Adding 10 to "threescore" thus produces 70. Psalm 90:10 goes on to say, "and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away." Biblehub.com interprets this statement to mean that living to the age of 80 entails much difficulty and pain. Both translations are from the King James Version of the Bible. Some other translations just say "70" instead of the more traditional "threescore and ten."