Deut 1:39 is a direct reference to the rebellion that occurred in Num 13 & 14. It was at this point that the Israelites had come to the borders of the promised land but refused to enter by trusting in God.
Because they refused to trust in God they uttered the fateful cry (Num 14:2):
And all the people of Israel grumbled against Moses and Aaron. The
whole congregation said to them, “Would that we had died in the land
of Egypt! Or would that we had died in this wilderness!
Be careful what you pray for!! God granted this request and all those 20 years and older died in the wilderness as stated by God in Num 14:29 -
Your bodies will fall in this wilderness—all who were numbered in the
census, everyone twenty years of age or older—because you have
grumbled against Me.
(See also Num 32:11.) Note the reference to the census. The Book of Numbers is characterized (and named) for the two times that a census was taken. In both cases, the people counted had to be 20 years and older -
- 1st census: Num 1:3, 18, 20, 22, 24, 26, 28, etc
- 2nd census: Num 26:2, 4.
Thus, "little ones" in this context (Deut 1:39) refers to those who were younger than 20 years old and not included in the census. That is while everyone 20 years and older in Num 13 died in the wilderness, those younger than 20 survived and became the inheritors of the promised land.