In the first year of his reign I Daniel understood by books the number of the years, whereof the word of the LORD came to Jeremiah the prophet, that he would accomplish seventy years in the desolations of Jerusalem.
I Daniel understood by books - rather, letters, i:e., Jeremiah's letter (Jeremiah 29:10, "After seventy years be accomplished at Babylon I will visit you, and perform my good word toward you, in causing you to return to this place") to the captives in Babylon; also Jeremiah 25:11-12; cf. 2 Chronicles 36:21; Jeremiah 30:18; Jeremiah 31:38. х bacªpaariym (H5612)] "By books" is made a plea for arguing that the prophecies attributed to Daniel were written subsequently to the return from Babylon, when first the canon of sacred Books was established. But doubtless the exiles of Babylon possessed private collections of the sacred writings, which are expressly referred to in Daniel 9:10-11.
Moreover х ceeper (H5612)], a book, when it is put in the plural, commonly means a letter. In 18 passages it means so elsewhere; and only in Ecclesiastes 12:12 means "books." The reference, therefore, is plainly to Jeremiah's letter (Jeremiah 29:10) (Tregelles). God's promises are the ground on which we should, like Daniel, rest sure hope; not as if the promises were to make our prayers needless, but rather to encourage them.