Or HaChaim on Numbers 26:4/אור החיים על במדבר כ״ו:ד׳

1 מבן עשרים שנה ומעלה, from twenty years old and up, etc. Why doesn't the verse tell us the subject matter this number is relevant to as it had done in verse two? Did Moses expect the Israelites to guess the significance of this number? If that were to be assumed, why did the Torah trouble itself in verse two to provide the information that people fit for military service were to be counted? According to what I have explained on verse three that the number (census) and the location i.e. the wilderness of Moav, were interconnected seeing that the objective of the census was to demonstrate that the number of Israelites had not diminished during the years Moses had been in charge, even the younger members of the people ought to have been counted in order to establish Moses' claim. What good would it do the people if the numbers of men fit for military service had not decreased but the number of potential soldiers had decreased due to the families being smaller or mostly girls being bom? Perhaps someone really thought that all the Israelites were counted on this occasion in order to prove Moses' claim that the people were at least as numerous as when Moses had taken over. To prevent us from arriving at that conclusion, the Torah repeated that only males above the age of twenty were included in this census. The reason Moses did not count people younger than twenty was "as G'd had commanded Moses." Had the census been up to Moses' discretion alone, Moses would not have bothered to count the Israelites at all, neither the men of military age nor the ones younger or older. By writing the words: "as G'd commanded Moses," the Torah states that the entire census was G'd's idea. This being so, there was no reason to include any age category in such a census which had not been included in a previous census.

2ובני ישראל היוצאים מארץ מצרים, and the children of Israel who took part in the Exodus from Egypt. It is quite unclear what the Torah intended with these words. Rabbi Avraham ibn Ezra suggests that the Torah meant that many of the people who were being counted now had actually taken part in the Exodus. Even if he is correct, why would the Torah consider it necessary to tell us about this at this point? Moreover, who needed Rabbi Ibn Ezra to tell us this? It is quite clear that many of the people who were below the age of twenty at the Exodus must have been included in this census! After all, the decree that the generation of the Exodus were to die in the desert after the debacle with the spies had applied only to people who had already reached the age of twenty either at the time of the Exodus or at the time the spies came back with their report! Perhaps it was the intention of the Torah to inform us that the result of this census produced a number equal to that of the census at the time the Israelites left Egypt as opposed to the number which resulted at the time the Israelites were counted at the beginning of the Book of Numbers. At that time the total amounted to 603,550 whereas this time the total was 601,730. In other words, the number was slightly lower than it had been some 38 years ago. The message then would be that Moses was not obligated to hand over to Joshua the same number of fighting men he had been able to muster at the time when he counted them earlier. The important thing was that he could show that he did not hand over fewer men than at the time of the Exodus. The census did prove this. [You will recall that I pointed out that the number at the Exodus included at least approx. 20.000 Levites so that Moses handed over far more men than he had at the time. Ed.] Another meaning of the words in question may be this: The number i.e. the census of Israelites on this occasion followed the same pattern as it had when they left Egypt, i.e. according to the houses of the respective tribal heads; Reuben according to the families of Chanoch, Phalu, Chetzron, and Carmi. Similarly, Shimon according to its tribal heads, i.e. Nemuel, Yamin, Yachin, Zerach and Shaul. This was in contrast to the count at the beginning of the Book of Numbers where the families of the tribes are not featured separately at all.