Adam Clarke on Jeremiah 29:10

For thus saith the Lord - It has been supposed that a very serious transposition of verses has taken place here; and it has been proposed to read after Jer 29:9 the sixteenth to the nineteenth inclusive; then the tenth, and on to the fourteenth inclusive; then the twentieth, the fifteenth, the twenty-first, and the rest regularly to the end.

That after seventy years be accomplished - לפי מלאת lephi meloth, "at the mouth of the accomplishment," or "fill to the mouth." Seventy years is the measure which must be filled; - fill this to the brim; - complete this measure, and then you shall be visited and released. The whole seventy must be completed; expect no enlargement before that time.