John Calvin Commentary Jeremiah 51:26

"And they shall not take of thee a stone for a corner, nor a stone for foundations; but thou shalt be desolate for ever, saith Jehovah." — Jeremiah 51:26 (ASV)

He confirms the previous verse: that when Babylon was destroyed, there would be no hope of restoration. It often happens that cities which have been completely destroyed are later built up again; but God says that this would not be the case with Babylon, for it was consigned to perpetual destruction. By corner and foundations he means the strength of the buildings. He then says that there was no hope that the stones would be fitted together again to rebuild the city, for Babylon would become a perpetual ruin or desolation.

We have, indeed, said that the walls of Babylon were not made of stones but of bricks; but the Prophet simply speaks in a common manner, to show that its ruin would be forever. We have also said elsewhere that the prophets commonly make a distinction between the people of God and the reprobate: God promises His Church a new state, like a resurrection from death, but He proclaims perpetual desolation for the unbelieving. Our Prophet now follows this pattern when he says that the desolations there would be forever, because there is no hope of pardon or of mercy for the unbelieving.