Among the Dead Sea scrolls are numerous texts of biblical books, which often differ in small—and sometimes large—ways from the standard version of the Hebrew Bible. Some of these differences are products of scribal errors; many scholars believe some Dead Sea versions to be the more accurate. In other instances, however, it seems that the scribes of Qumran (the community to which the scrolls belonged) deliberately interpolated their ideas into the texts, as Shani Tzoref writes:
For example . . . a copy of the book of Samuel contains some text that is not preserved in the Masoretic text [i.e., the standard Jewish version] of Samuel or in other biblical versions. The beginning of 1 Samuel 11 describes how the Ammonite king Nahash set brutal terms of surrender upon the men of Jabesh Gilead—demanding that the right eye of every man be gouged out. The Qumran manuscript provides some context for this demand, with an account of Nahash’s prior suppression of a rebellion by the tribes of Reuben and Gad, in which he gouged the eyes of the rebels as punishment. Though some scholars view the absence of this account in the Masoretic text as a copyist’s mistake, others have explained the extra material . . . as an ancient interpretive expansion.
In some cases of extensive revision or rearrangement of the biblical text, scholars have even debated whether to consider certain [Dead Sea] compositions to be scriptural works. For instance, the Psalms Scroll from cave 11 contains 41 psalms that are found in the Masoretic text but in a different order, as well as an additional seven psalms and a prose passage about King David’s prodigious poetic output—according to this passage, David composed not only the psalms now in the Bible but also more than 4,000 others!