John Calvin Commentary Psalms 126:4

"Turn again our captivity, O Jehovah, As the streams in the South." — Psalms 126:4 (ASV)

O Jehovah! Bring back our captivity. The second part of the Psalm, as I have said, contains a prayer that God would gather together the remnant of the captives. The Holy Spirit inspired this form of prayer for the Jews who had already returned to their homeland, that they might not forget their poor brethren who were still in exile.

All the Jews, no doubt, had a door opened to them, and perfect liberty granted them, to come out of the land of their captivity, but the number of those who received this benefit was small when compared with the vast multitude of the people. Some were kept from returning by fear, and others by sloth and lack of courage, on seeing such perils before them which they perceived they lacked the power to overcome, choosing rather to remain torpid in their own filthiness than to undertake the hardship of the journey.

It is also probable that many of them preferred their present ease and comfort to eternal salvation. What the Prophet Isaiah had foretold was no doubt fulfilled (Isaiah 10:22): That although the people were in number as the sand of the sea, yet only a remnant of them should be saved.

Since, then, many openly refused the benefit when it was offered them, and as there was no lack of difficulties and impediments to be encountered by those who availed themselves of this liberty granted by the king's good pleasure, so that it was only a few of sounder judgment and of a more intrepid heart who dared to move a foot—and even they with reluctance—it is no wonder that the Prophet requires the Church still to make supplication to God for the bringing back of the captivity.

Along with this, the state of those who had already returned should also be noted. Their land was in the possession of strangers, who were all their inveterate and sworn enemies, so they were no less captives in their own country than among the Babylonians. It was therefore necessary, for two reasons, that the Church should earnestly beseech God to gather together those who were dispersed:

1. that he would give courage to the timid, awaken the torpid, cause the besotted to forget their pleasures, and stretch forth his hand to be a guide to all; and
2. that he would settle the body of the people who had returned in liberty and ease.

As for the simile that follows, many think the meaning is that the bringing back of their captivity, which was prayed for, would be as welcome to them as if water should flow through a desert. We know how grievous and painful it is to travel in a hot country through arid sands.

The south is understood as the wilderness, because the region south of Judea was desolate and almost uninhabitable. Yet it seems more accurate to me to say that the grace of God is here magnified and further emphasized by the Prophet’s comparing it to a miracle. “Although it is a difficult matter,” he essentially says, “for the dispersed remnant to be reunited into one body, yet God, if he pleases, can do this, just as he can cause rivers of water to flow through a parched desert.” He also alludes to the road between Judea and Babylon, as is apparent from the locations of the two countries.

Thus the words do not require any supplement, the meaning being simply this: that the bringing back of their captivity would be as if a river should run through a barren and parched country. And certainly, to open up a way for the people who, so to speak, were swallowed up in a deep gulf, was as if a course had been opened up for irrigating waters to flow through a desert.