“The tribes of Reuven and Gad approached Moses and said: We will build enclosures for our flocks here and cities for our children. We will arm ourselves quickly and go ahead of the Children of Israel until we will have brought them to their place. Our children will dwell in fortified cities because of the inhabitants of the land” (Numbers 32:16-17).
It is important to pay careful attention to Moses’ response to this request from the tribes of Reuven and Gad to remain on the other side of the Jordan River rather than settling in the land of Canaan proper. They wanted to make it clear to Moses that they were not going to ignore their responsibility to take part in the conquest of the land.
In verse 24 Moses says: Build yourselves cities for your children and pens for your flocks; whatever you have expressed verbally, you must fulfill. While it seems that Moses just reflected their commitment back to them, there are two vital differences in the wording.
The author of HaKsav v’HaKabbalah points out that Reuven and Gad displayed a less than sterling trait by speaking about their flocks before their children. In fact, it may not be possible to fully trust such people. Therefore, Moses instructs them to first take care of their children and then worry about their possessions. This will demonstrate that they are decent people who can be relied upon to fight along with their brethren to conquer the land west of the Jordan River.
(It is interesting that there are 112 verses in the Torah portion of Mattos. The Hebrew word “l’vanecha” – to your children, has the numerical value of 112. This helps emphasize that our priority in life has to be on our children with concerns of prosperity of secondary importance).
A second difference is discussed in Sefer Gan Raveh. Note that the tribes of Reuven and Gad seemed to place their trust in their own defensive abilities and stressed that they were going to build fortified cities. Moses, however, urged that they focus on placing their trust in Hashem and to simply build normal cities.