John Calvin Commentary Numbers 26:28

"The sons of Joseph after their families: Manasseh and Ephraim." — Numbers 26:28 (ASV)

The sons of Joseph after their families. The comparison of the two tribes, which sprang from the same head, is worthy of notice. Because Manasseh was the father of only one son,¹⁹⁴ the prophecy of Jacob, when he declared that the first-born would be inferior to his younger brother Ephraim, already began to be fulfilled. Nevertheless, God’s blessing extended far and wide for the increase of his family, so that they exceeded the tribe of Reuben in number. Furthermore, though the larger number of children (πολυτεκνία) in which the descendants of Ephraim were superior was a kind of type of his promised fruitfulness, still the excellence and dignity, of which Jacob prophesied, were deferred to a distant period; since in this respect the tribe of Ephraim was inferior by about a third, whereas more numerous offspring had been promised him. Although, therefore, God had not spoken in vain, yet the fulfillment of His promise did not immediately appear.

In the tribe of Dan, however, the incredible power of God was displayed. He was contemptible among his brothers; and for that reason, it was an extraordinary blessing granted to him in the form of an honorable status and name when Jacob declares that Dan shall judge his people (Genesis 49:16). He is said to have fathered only one son; yet his posterity exceeded 64,000.

¹⁹⁴ There appears to be an oversight here: see Joshua 17..