John Calvin Commentary Numbers 7:12

"And he that offered his oblation the first day was Nahshon the son of Amminadab, of the tribe of Judah:" — Numbers 7:12 (ASV)

And he that offered his offering the first day The oracular declaration which God made by the mouth of Jacob is well known: The scepter shall not depart from Judah, etc. (Genesis 49:10). Now, although the time had not yet arrived when the truth of this prophecy should be manifested by its fulfillment, it was nevertheless brought to pass by the admirable counsel of God that certain marks of supremacy should exist in the tribe of Judah; and, by general consent, if not dominion, at least the chief dignity was always lodged in it.

The assignment of the first day to Nahshon was, therefore, a presage of that future kingdom which was eventually set up in the person of David.

If anyone should allege the absurdity that the tribe of Reuben, the first-born, should be kept back until the fourth day, I reply that the tribes of Zebulun and Issachar were ranked under the banner of Judah, since it will appear in chapter 10⁴⁰³ that the twelve tribes were divided into four divisions of three.

Thus, it was more honorable for the tribe of Reuben to have the fourth day, so as to have the two tribes over which it presided attached to it. But the fathers of the two tribes which God placed under the banner of Judah were the two youngest sons of Leah, who followed next after Judah, her fourth son.

We see, therefore, that the kingdom from which salvation was to be hoped for by the whole people was thus obscurely shadowed forth: in order that they might be more attentive to the promise given them; although this indication of it had little effect on their sluggish minds.

⁴⁰³ “Que la compagnie a suyvi son chef: car les douze lignees,” etc.; that the company followed its chief; for the twelve tribes, etc.— — Fr.