Translation:

13. (It is) in Books held (greatly) in honor.

Notes (Tafseer)

5956. At the time this Sura was revealed, there were perhaps only about 42 or 45 Suras in the hands of the Muslims. But it was a sufficient body of Revelation of high spiritual value, to which the discription given here could be applied. It was held in the highest honor; its place in the hearts of Muslims was more exalted than that of anything else; as Allah's Word, it was pure and sacred; and those who transcribed it were men who were honorable, just and pious. The legend that the early Suras were not carefully written down and preserved in books is a pure invention. The recensions made later in the time of the first and the third Khalifas were merely to preserve the purity and safeguard the arrangement of the text at a time when the expansion of Islam among non-Arabic-speaking people made such precautions necessary.