Charles Ellicott Commentary 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 the Euphrates:" — Jeremiah 51:63 (ASV)

You shall bind a stone to it. —The meaning of the symbolic act, which has its parallel in the girdle of Jeremiah 13:1-7, in the potter’s vessel of Jeremiah 19:10, and in the yokes of Jeremiah 27:2, is explained in the following verse. The parchment roll by itself might have floated, and been picked up and read, and so the stone was tied to it that it might sink at once, and thus prefigure the destruction of the city. (Compare the reappearance of the symbols in Revelation 18:21, in connection with the destruction of the mystical Babylon.)