John Calvin Commentary Deuteronomy 33:18

"And of Zebulun he said, Rejoice, Zebulun, in thy going out; And, Issachar, in thy tents." — Deuteronomy 33:18 (ASV)

And of Zebulun he said. He compares two tribes with each other, which, although neighbors in location, were still very dissimilar. One, being devoted to mercantile pursuits, often went out in various directions; the other took more delight in quiet and rest. This great variety in their condition is indicated when he tells Zebulun to rejoice in its expeditions, and Issachar in its rest at home. Moses thus confirms the prophecy of Jacob, who said that Zebulun should dwell at the haven of the sea, so as to make voyages of trade; while Issachar, delighting more in rest, should be lazy and idle, so as not to object to paying tribute to purchase peace (Genesis 49:13–15).

I suppose what follows was added as if Moses had said that their distant location should not prevent them from going up with the others to Jerusalem to perform their religious duties. Because they were further removed from the temple, their zeal in the legal service might have grown cold. Although, then, they lived in the outermost borders of the land, Moses says that they should nevertheless come to offer sacrifices to God.

Some understand the peoples to mean the other tribes, which does not seem at all consistent; others understand it as foreign nations, to which their commercial dealings gave them access. My interpretation, however, is simply that, although the length of the journey might tempt them to remain at home, they should still mutually encourage each other to go in large companies to the temple.

The end of the verse may state a reason for this, as if to say that they will be more attentive to the service of God because, being enriched by Him, they will desire to offer Him praise. And certainly, it is a sign of gross ingratitude when we are not stimulated by God’s blessings to strive more earnestly to give Him thanks, in proportion as He deals more generously with us.

At the same time, Moses shows that, considering their great wealth, the expenses of the journey would by no means be burdensome to them. For, although their country was not very fertile, its position was still most advantageous for acquiring riches.

Thus, when it is said here, they shall suck of the abundance of the seas, an antithesis should be understood between the fruits of the earth and the abundant revenues derived from trade. To the same effect, the treasures hid in the sand are spoken of. The explanation given by some—that their treasures would be so great that they would hide them in the sand, or that the sands there would be so prolific in silver and gold, or that they would collect what the sea cast ashore—is poor and dull. Therefore, while others would grow rich from their lands, Moses says, using an elegant figure, that the sands of Zebulun would be filled with hidden treasures because of their foreign trade.