Jeremiah 51:63

And it shall be, when thou hast made an end of reading this book, that thou shalt bind a stone to it, and cast it into the midst of Euphrates:

Cross-reference

Revelation 18:21 echoes this symbolic act — an angel throws a millstone into the sea to depict Babylon's final fall.

Exodus 15:5 uses the same sinking-stone imagery — the Egyptian army sank like a stone, just as Babylon will sink.