New Revised Standard Version
David did not count those below twenty years of age, for the LORD had promised to make Israel as numerous as the stars of heaven.

Contemporary English Version
When David decided to count the people of Israel, he gave orders not to count anyone under 20 years of age, because the LORD had promised long ago that Israel would have as many people as there are stars in the sky.

New American Bible
David did not count those who were twenty years of age or younger, for the LORD had promised to multiply Israel like the stars of the heavens.

Douay-Rheims Bible
But David would not number them from twenty years old and under: because the lord had said that he would multiply Israel like the stars of heaven.

But David would not number them from twenty years old and under: because the lord had said that he would multiply Israel like the stars of heaven.

from twenty

Numbers 1:18 And assembled them on the first day of the second month, reckoning them up by the kindreds, and houses, and families, and heads, and names of every one from twenty years old and upward,

he would increase

Genesis 15:5 And he brought him forth abroad, and said to him: Look up to heaven and number the stars if thou canst. And he said to him: So shall thy seed be.

Hebrews 11:12 For which cause there sprung even from one (and him as good as dead) as the stars of heaven in multitude and as the sand which is by the sea shore innumerable.