Kommentar zu Bamidbar 1:20

בכור ישראל. He had not lost his status in the books kept in heaven as he had repented his sin as testified in Genesis 35,22-23 commencing with the otherwise unnecessary words ויהיו בני יעקב שנים עשר, “that Yaakov’s sons remained twelve.” This was in contrast to Reuven’s birthright privileges here on earth having been revoked in favour of Joseph.

כל יוצא צבא, all who were able to go to war. The Torah repeats this comment every time the number of males in a tribe is given. This is because the Torah wants to tell us that amongst all the males over the age of twenty counted there was not even one who was physically unfit to go to war.

V. 20. ויהיו בני ראובן וגו׳. Die Reihenfolge der Stämme, in welcher sie zur Zählung kamen, entspricht ganz ihrer Gruppierung in מחנות, wie sie das zweite Kapitel enthält (über diese siehe daselbst).

ויהיו בני ראובן בכור ישראל, “the number of males counted of the tribe of Reuven, Yaakov’s firstborn son was etc.” this is pointed out, as when it came to the marching in order of the tribes, Yehudah was the first. Reuven was mentioned here first is that he was Yaakov’s firstborn son.

ויהיו בני ראובן, “and the members of the tribe of Reuven, (the males over 20 years) amounted to, etc;” the tribes (excluding the tribe of Levi) were counted there one after another, in the order of their respective flags. Therefore Moses began with Reuven, followed by Yehudah the leader of all the tribes, followed Ephrayim and Dan.

במספר שמות לגגלתם, “according to the number of their names, head by head.” Why does the word לגלגלתם occur only in connection with the members of the tribe of Reuven and Shimon, and none of the other tribes? The reason is that when Yaakov spoke to each of his sons prior to dying, he chided both Reuven and Shimon, instead of giving them an outright blessing. They were therefore in need of atonement, forgiveness. The function of counting by means of the silver coins was in order to achieve atonement, [although these descendants had no special need to atone for the sins of their forefathers. Ed.] At any rate, Moses wished to assure them that they had no longer any need for atonement.

ראובן בכור ישראל, “Reuven, Israel’s firstborn;” this point had to be made again as the first tribe in the marching order was Yehudah. (B’chor shor) The reason why this point was made by the Torah at this juncture, was to explain that the only reason why he was counted first was that biologically, he was the first son of his father.