Daniel 9:2

by the books i.e. the sacred books, the Scriptures. The neglect of the Heb. article in the A.V. obscures here an important point; for - thebooks" can only be naturally understood as implying that, at the time when the passage was written, some definite collection of sacred writings already existed (comp. Ryle, Canon of the Old Test., p. 112). We do not however learn more respecting its contents except that it included the prophecies of Jeremiah. The phrase might also be rendered (Hitz., Keil, Behrm.) observed in the books.

which the word of Jehovah came to Jeremiah the prophet that he would accomplish for the desolations of Jerusalem, (even) seventy years] See Jeremiah 25:12, and especially Jeremiah 29:10, which, being followed by promises of restoration, addressed to Israel, seems to have been particularly in the writer's mind. Cf. 2 Chronicles 36:21.