Albert Barnes Commentary Psalms 65:12

"They drop upon the pastures of the wilderness; And the hills are girded with joy." — Psalms 65:12 (ASV)

They drop upon the pastures of the wilderness - This refers to the desolate places, or the uncultivated parts of the land—the places of rocks and sands. The word "wilderness" in the Scriptures does not mean, as it does for us, a tract of country covered with trees, but a place of barren rocks or sands—an uncultivated or thinly inhabited region (see the notes on Matthew 3:1 and Isaiah 35:1).

In these desolate areas, however, there would be valleys, or places watered by springs and streams, that would provide pastures for flocks and herds. Such are the “pastures of the wilderness” mentioned here. God’s passing along these valleys would seem to “drop,” or distill, fertility and beauty, causing grass and flowers to spring up in abundance and clothing them with luxuriance.

And the little hills rejoice on every side - The margin, as in Hebrew, reads, "are girded with joy." This means that joyful, happy scenes surround them, or they seem to be full of joy and happiness. The valleys and the hills alike appear to be made glad. The following remarks from Professor Hackett (“Illustrations of Scripture,” p. 30) will explain this passage: “Another peculiarity of the desert is that, although the soil is sandy, it rarely consists of mere sand for several days in a row; it is interspersed, at frequent intervals, with clumps of coarse grass and low shrubs, providing very good pasture, not only for camels, the natural inhabitants of the desert, but also for sheep and goats. The people of the villages on the borders of the desert are accustomed to lead out their flocks to the pastures found there.

We frequently passed shepherds engaged in this way on our journey; and it was interesting to observe, as a verification of what is implied in the Savior’s statement (Matthew 25:33), that the sheep and goats were not kept distinct but were intermixed with one another. The shepherds not only frequent the parts of the desert near their homes but often go a considerable distance from them; they remain absent for weeks and months, only changing their location from time to time, as their needs for water and vegetation may require. The incident related concerning Moses shows that the pastoral habits of the people were the same in his day: Now Moses kept the flock of Jethro, his father-in-law, the priest of Midian; and he led the flock to the further part of the desert, even to Horeb, (Exodus 3:1). It is of the desert in this sense, as supplying to some extent the means of pasture, that the prophet Joel speaks (Joel 1:19; Joel 2:22).”

The psalmist also says (Psalms 65:12–13), with the same reference:

Thou crownest the year with thy goodness,
And thy paths drop fatness;
They drop fatness on the pastures of the wilderness.